Words  & Definition


The Internet of  Things (IoT) describes the network of physical objects— “things”—that are  embedded with sensors, software, and other technologies for the purpose of  connecting and exchanging data with other devices and systems over the  internet.


A device that  provides a usable output in response to a specified measurement.

Machine 2  Machine (Machine 2 Machine)

Machine-to-machine, or M2M, is a broad label that can be used to  describe any technology that enables networked devices to exchange information and perform actions without the manual assistance of humans.

Cloud  Computing

cloud computing  is the delivery of computing services—including servers, storage, databases,  networking, software, analytics, and intelligence—over the internet (“the  cloud”) to offer faster innovation, flexible resources, and economies of  scale.

Wireless  Sensor Network (WSN)

An IoT (Internet  of Things) Wireless Sensor Network (WSN) refers to a group of spatially  dispersed and dedicated sensors for monitoring, and recording the physical  conditions of the environment, and collectively pass on such data through a  wireless network to a internet-based location.


Radio Frequency  Identification (RFID) refers to a wireless system comprised of two components: tags and readers

Edge Computing

Edge computing  is an emerging computing paradigm  which refers to a range of networks and devices at or near the user.

Big Data

The definition  of big data is data  that contains greater variety, arriving in increasing volumes and with more  velocity. This is also known as the three Vs. Put simply, big data is larger,  more complex data sets, especially from new data sources.

Smart Home

A smart  home allows homeowners to control  appliances, thermostats, lights, and other devices remotely using a  smartphone or tablet through an internet connection.

Smart Grid

A smart grid is  an electricity network that uses digital and other advanced technologies to  monitor and manage the transport of electricity from all generation sources  to meet the varying electricity demands of end users.


Software  that is stored on a device itself. Regular computers have very little  firmware, since software mostly comes from a hard drive or some other  storage.  But on IoT devices, much of the software may be firmware.


For our purposes, it’s the  removal of all unnecessary details, leaving only what’s required for  operation.


Alternating current (which is also alternating voltage). This is  how power is delivered to homes and factories.


A circuit, usually done with hardware instead of software, that  can perform some task faster than a processor can.  Instead of the processor handling the task itself, it offloads the work to  the accelerator, and the accelerator sends the answer (whatever that means  for the  task) back to the processor.


 A sensor that  measures acceleration and deceleration.

Access  point

For wireless  network connections like WiFi, this is a router that takes your wireless  signal and either connects it to other wireless signals or to a wired signal  — say, for going to the cloud.


A way of  controlling some device electronically. It might turn the device on or off or  change a setting or property or do any other thing that the device is capable  of.


A way of calculating something, typically as a step-by-step recipe.  A familiar one to all of us is how we do long division on paper: that’s an algorithm. Algorithms abound in the IoT.


A group of  companies working together (in an anti-trust fashion) to promote a particular  protocol or set of protocols. They’re like a standards body, but they don’t  have the official imprimatur of a standards body.


Refers to rummaging through lots  of data to learn things. This would be done by an IoT device or service  provider. For instance, looking at what time of day a gadget gets used most,  or seeing if any devices have failed.


Taking data  that originated from an individual IoT device user and stripping off any  parts of the data that can tie the data to that individual. The data then  becomes anonymous.


Refers to laws preventing  competing companies from anti-competitive behaviour.

Application  programming interface

Commands or  functions that let a programmer control some other program or object or  thing, or get data from some object, without knowing the details of how it  works.

Artificial intelligence

broad term for technology that acts more human-like than a typical  machine, especially when it comes to “thinking.” Machine learning is one  approach to AI.

Artificial neural network

A type of  neural network that’s loosely inspired by biological neurons but operates  very differently.


An older way  of representing characters (letters, numbers, and punctation) in computers.  It could handle only characters relevant to English and languages using those  characters. It has mostly been replaced by Unicode, which can represent all  the world’s characters.


A software  development tool that takes a low-level assembly-language program (source  code) and translates it into a machine-language program (object code).

Assembly language 

This is a more  human-readable version of machine language. It’s still low-level, but it uses  text instead of 1s and 0s.

Asymmetric key

A way of  encrypting data that uses one key for encrypting and another for decrypting.

Attack surface

 Industry  jargon for a way to break into a device or network or anything.


A security  operation that involves “inspecting” software (and perhaps also data) to  check whether anything has been altered.


This is the  act of proving to some other entity that you are truly who you are  representing yourself to be. That is, you’re not pretending to be someone  else. “You,” of course, means a computer or IoT device or any other entity  trying to make a network connection with another computer or device.


The process of  deciding what privileges – if any – someone gets on a network, server, or  other asset.


A specific  range of frequencies. Usually smaller and more specific than what’s referred  to by spectrum. You would refer to the AM radio band,  not the AM radio spectrum. That’s where CB – Citizens’ Band –  comes from.

Bare metal

Describes a  system that has no OS. Software runs directly on the hardware.

Best practices

A term  referring to ways of doing things (business, technology, etc.) that an  industry generally views as the best way to do things. Best practices take  time to establish, and they usually relate to basic principles, leaving lots  of options on how to do specific things.


A base-2  counting system (rather than the base-10 system we usually use). Digits can  be 0 or 1.


The smallest  unit of information. It is a shortened form of “binary digit.” Since it’s  binary, it can have only two values — typically 0 and 1.

Bit cell

A cell that  stores a single bit within a memory. (Some can store more than one bit.) It  connects a word line to a bit line. The bit cell can either conduct or not  conduct current; those are the two states of the memory cell.

Bit line

A line in memory that can detect whether a bit cell conducts  current. This is how the memory is read. The bit lines and word lines are  orthogonal to each other, making an array of the bit cells that connect them.


An electronic  ledger system where all entries are confirmed by some decentralized  mechanism, like voting, and cryptographically attested so that, if someone  changes one entry anywhere, it will be obvious.


In the context  of a thread, refers to execution that may have to wait for a result to come  back before it can proceed. While waiting, it’s said to be blocked.

Boot code

Software that  loads and runs when a device first powers up.


Used as a  verb, indicates taking a device that performs some function and eliminating  or disabling that function. It’s considered no better than a brick at that  point.


A server that  manages published data and subscribers to that data as part of a  publish-and-subscribe setup.


A way of  connecting the components of a computing system where the components all  share the same wires, but a controller makes sure that only one device can  put its signals on the wires at a time.

bus protocol

The  “rules of the road” for a specific bus. Determines how a bus controller  decides who gets access to the bus when.

business rules

Rules  that say, “if this happens, then do that.” Like, “if the ground is too dry,  then turn on the sprinkler.”


A byte is  8 bits.


A  programming language that gives low-level control of all the details.


A place  to park data coming from slow memory so that you can access it quickly. It’s  built with SRAM memory, but it’s organized so that you can figure out which  parts haven’t been used in a while so that they can be replaced with new  cached items. Also, if you make a change to cached data, that change has to  make its way back into the original slow storage.

cache hit

Refers  to the situation where you need memory.

data  that’s already in the cache.

cache miss

Refers to  the situation where you need memory data that’s not already in the cache, so  you first need to load it from slower memory into the cache.


Capacitance  is the ability of an electron or hole to “feel” other electrons or holes on  the other side of a small gap. The gap prevents actual current from flowing,  but, if small enough, electrons and holes can pile up on either side of the  gap. Specific devices that make use of this are called capacitors.


A digital  document that certifies, more or less, that someone is who they say it is.  It’s issued by a certificate authority.

certificate authority

A trusted  organization that issues security certificates.


An  electronic device made on a piece of silicon. These days, it could also  involve a mechanical chip, but, to the outside world, everything looks  electronic. The chip is usually in some kind of package; that package might  contain multiple chips. “Integrated circuit,” and “IC” mean the same thing,  but refer only to electronic chips, not mechanical chips.


Consumer  Internet of Things. IoT gadgetry designed for home and personal use.


Complex  Instruction Set Computer; a kind of processor architecture that may have  many, many instructions that are complicated and specialized. This term  contrasts with RISC.


A way of  connecting MOS (metal-oxide-semiconductor) transistors into a switch that  conducts no current when sitting idle.


A type of  artificial neural network specifically used for machine-vision applications.


A  communications protocol that uses the RESTful approach for small systems such  as those used for the IoT.


Competing  companies getting together to reduce competition by agreeing on pricing or  splitting up territories or in other ways arranging not to compete. This kind  of collusion is, at least in the US, illegal (although enforcement isn’t  guaranteed).


In its  electronic version, a magnetometer that has its reading compensated by a tilt  meter (done by an accelerometer).


A  software development tool that takes a high-level program (source code) and  translates it into a low-level machine-language program (object code).

computer farm

A  collection of computers that are interconnected so that they can share and  distribute work. For our purposes, it’s the same as a data center, but the  focus is on the collection of computers.


The  literal opposite of resistance. Rather than how hard is it to push the flow  through, it looks at how easy it is. Measured in mhos.


A  material through which electricity can flow. Metals are a good, familiar  example.


This  refers to some kind of electrical connection. It might be through a network  cable, a cable connection, a wireless connection, or a phone – just to name  some options. The connection might be to the internet or to some other local  device.


A way of  separating applications running on the same server. It’s lighter weight than  a full virtual machine.

context switch

Refers to  a CPU changing from one thread to another, with all of the related  information from one thread being stored and replaced by the same type of  information for the new thread.


An  agreement on some decision that could be made several ways. For example,  given a single bit, you could decide that 1 means “true” and 0 means “false,”  or you could decide the opposite. Similar in spirit to a protocol, but  protocols usually deal with how something is done — a step-by-step process,  for example.


This can  have more than one meaning.

When  discussing networks, the core is the heart of the network where much of the  traffic (or at least that part that must go a long way to its destination)  moves. This contrasts with the edge — the outer part of the network where  devices like computers and printers get connected.

When  discussing computers, you can think of it as the same as a CPU.


Stands  for “central processing unit.” Basically, it’s a microprocessor – the main  one in the computer. Things get a bit more complicated because, these days,  there may be more than one microprocessor. But you can safely think of all of  them together as the CPU.


A form of  artificial currency that uses blockchain technology. Bitcoin and Ethereum are  better-known examples.


The  amount of electrical flow. Measured in amperes or amps (A).

data analyst

Someone  whose job it is to go through accumulated data to learn something from the  data.

data center

A  collection of computers that are interconnected so that they can share and  distribute work. For our purposes, it’s the same as a computer farm, but the  focus is on its application for processing data.


 A  structured way of storing data and relating different pieces of data to each  other. (Like, which address belongs to which person.) There are “query”  languages, the best-known of which is SQL, that let you enter data into the  database, change data that’s already in the database, and retrieve data from  the database.


Direct  current (which has constant voltage). This is what electronics require as an  energy source.

Dead reckoning

The  process of determining your position through a series of speed and heading  calculations. Small errors can accumulate if your measurements and those  calculations aren’t accurate enough.


The  base-10 counting system that we usually use. Digits can go from 0 to 9.


This is  the process of “unregistering” an IoT device that you’re not going to use  anymore. It keeps someone else from using it (if it’s lost or stolen).

Degree of freedom

A setting  or property that can be adjusted independently without affecting any other  setting. With movement, there are three straight-line degrees of freedom:  forward/backward, up/down, and left/right.


 This  generically refers to how data can be received on some physical medium – like  a wire or a radio signal. Voltages might be moving up and down, or the  frequency of some periodic signal might be changing. There are lots of ways  of “coding” data so that it can travel across the medium. It’s a low-level  detail; most of us don’t need to know any of the fine print. The opposite of  demodulation is modulation, and a piece of network equipment that does both  (modulation for sending, demodulation for receiving) is called a “modem.”


In a  computer program, refers to the situation where one piece of the program  depends on the result of some other part of the program. If we calculate 1+1,  then there’s no dependency. If we calculate a+b, then our result depends on  whatever prior calculations produce a and b.


 A means  by which materials can be added to a silicon wafer.


 In the  context of machine vision, a task that identifies the particular type of  object in the image – chair, person, cat, etc.


The  result of a hashing operation.

Digital signal processing

A  processor optimized for handling computations involving digital  representations of analog signals.

Digital signature

An  encrypted digest that can be appended to a message or sent separately from  the message.

Digital twin

A virtual  version of a specific piece of hardware – airplane engine, car, etc. – that  behaves like and mirrors the true hardware version, keeping in synch with it.  Such models can often be used to predict things like wear-out before they  happen.


An  electrical component that allows current in one direction but blocks it in  the other direction.

Distributed computing

A way of  breaking up calculations and letting more than one computer work on different  pieces at the same time in order to speed up the solution.


Stands  for “dynamic random-access memory.” This is temporary working memory in a  computer. When the power goes off, the memory contents are lost.  It’s not super-fast, but it’s very cheap, so there’s lots of it.


Datagram  transport-layer security. This is a security protocol analogous to TLS.  TLS is used with TCP; DTLS is used with UDP (which sends so-called datagrams).  Some version of this or TLS should be in IoT devices.

Dynamic power

The rate  of energy consumption of a circuit while it’s switching — that is, while  computing or otherwise doing work.


A group  of related businesses that agree to work together, typically through a  somewhat formal organization that may have a brand name. If something like  that existed, for, say, produce sold in a grocery store, then the ecosystem  might include select farmers, distributors, transportation companies, and  grocery stores.


This term  is slightly confusing because, in different contexts, in means slightly  different things. In general, when talking about networks, it refers to that  part of the network where devices (computers, printers, etc.) are connected.  That’s in contrast to the core, which is the middle of the network where lots  of traffic gets moved around.


 A  fundamental particle found outside atoms. It carries a negative charge. It  can move easily in a conducting material, which gives rise to electrical  current.


Refers to  one kind of system that can behave as if it were another kind. A good example  is a Macintosh, which, by itself, works very different from an  Intel/Microsoft-based PC. But a Mac can pretend to be a PC by emulating how a  PC works.


In the  context of chip design, a specialized computer that can implement a model of  a chip design for testing that design thoroughly prior to building real  chips.


When the  details of how something works is buried inside the code for an object in a  way that lets some other programmer use it without knowing those details, we  say that the details have been encapsulated.


Encryption  refers to encoding and decoding (or encrypting and decrypting) data so that  it can’t be read unless you have the right key. It’s critical for good  security.

Energy harvesting

Technology  that can grab energy from the environment for local use with low-power  devices.


 A very  common Layer 1 and 2 standards for wired network connections.

Flash memory

A type of  memory that can retain its contents even with the power off. Thumb drives use  flash memory.


This can  have two different contexts.

For  message packets

When the  contents of a message are too long for a packet, then the message is  fragmented into multiple packets for sending, and those fragments are  reassembled on the receiving end of the message.

For  memory

A  situation where free memory is broken up into small pieces throughout the  memory rather than accumulated at one spot. This makes it harder to allocate  the free memory, since the small pieces may be too small for a new allocation  request.


The rate  of change of a signal, specified in hertz, or cycles per  second.


Fear,  Uncertainty, and Doubt. This is a sales tactic used to confuse someone about  the competition. The information may or may not be true, but using FUD is  often seen as a somewhat desperate way to get a sale.


A small  portion of a program that’s set aside and given a name. It helps isolate key  code in an easy-to-understand way, and it makes changes easier and less error  prone. It’s a really important way to make programs easier to understand. May  also be called a subroutine.

Garbage collection

The  process of defragmenting memory by moving multiple free “holes” in memory  together so that they can be allocated more effectively.


A piece  of electronic network equipment that takes a local network and gives it  access to the internet. Your cable modem, for instance, might act as a  gateway.

General  Data Protection Regulation

A set of  privacy rules governing how EU residents’ personal data must be handled.


Global  Navigation Satellite System. A generic name for the various location  satellite systems that exist, like the US’s GPS and Russia’s GLONASS.


Global  Positioning System. A satellite system that sends signals to earth. GPS  receivers can get those and figure out where on the earth you are. This is  specifically a US-based system, an example of the more generic term “GNSS.”


Global  Positioning System. A satellite system that sends signals to earth. GPS  receivers can get those and figure out where on the earth you are. This is  specifically a US-based system, an example of the more generic term “.”

Graphics processing unit

A  processor optimized for rendering images and video on a display.


A sensor  that detects when it changes direction.


This can  mean a couple things. A quick-and-dirty (but not elegant) trick to get  something done is a hack. A computer security break-in is also a hack  (because inelegant tricks are used to break in). It can be a noun or a verb  (“he hacked my computer”).


A  misused, but common term for an unauthorized person trying to break into a  device or network. Originally, in this context, “hackers” referred to the  good guys (or “white hats”), while “crackers” were the bad guys (black hats).

Hard drive

A type of  persistent (non-volatile) memory built from rotating platters and “read  heads” that sense the data on the platters.


In this  context, “hardware” refers to functions in an IoT device that are built into  a silicon chip or some other dedicated component. It’s distinct from  “software,” which refers to instructions running on a processor.

Hardware root of trust

A chip of  some sort that stores security artifacts like keys and certificates. It can  perform the security operations itself so that those artifacts never have to  (and can never) leave the chip.


A way to  combine the contents of a message to generate a value that is almost unique  to that message.

Heap memory

A block  of working memory reserved for use by programs as they request an allocation.  The programs request and release memory from the heap as they go, and where  specific data will end up in the heap is unpredictable.


The unit  used for frequencies. It’s abbreviated Hz. Equivalent to cycles per  second. A periodic signal that completes a cycle in one second is said to  have a frequency of 1 hertz, or 1 Hz.


A measure  of frequency, or how often something repetitive can happen in a given time.  Specifically, it means one cycle per second.


A base-16  counting system (rather than the base-10 system we usually use). Digits can  go from 0 to 9 and then A, B, C, D, E, and F.


In a  material with specific places where electrons should be (like silicon), if an  electron moves out of its designated spot, what’s left is called a hole.  A hole effectively has a positive charge, and, as electrons move from hole to  hole, it looks like the hole moves (even though, strictly speaking, it  doesn’t – it just gets filled or emptied by a moving electron).


The main  processing unit in a system. It controls how all other processors in the  system operate. It’s the boss.


A piece  of electronic equipment that gathers separate related things together. A  network hub, for instance, might bring together the individual network  connections of multiple local users. A sensor hub brings together sensor data  from multiple separate sensors for possible combination.

Or, more  specifically, a device in the home (or elsewhere) that acts as a central  point connecting a variety of smart-home (or other) devices. The devices talk  to the hub; the hub talks to the cloud.


Stands  for input/output. This refers to the signals that come into and  depart from the computing system (as opposed to the signals running internal  to the computing system).


A  property of a command or operation such that doing it once or more than once  yields the same result.


Industrial  Internet of Things. A broad collection of factories, automotive,  agricultural, medical, and other areas where IoT technology is used.


The  tendency for an object to keep moving (or not moving) at a constant speed if  you don’t accelerate or decelerate it. There’s inertia in a straight line and  there’s also inertia of rotation – spinning things want to keep rotating in a  specific direction unless you force them to change.

inertial measurement unit

A sensor  that uses inertia to measure acceleration or deceleration either in a  straight line or in rotation.

A combination  sensor with an accelerometer and a gyroscope, and, often, with a  magnetometer. The first two rely on inertia to tell you where you are and  where you’re going.


For  machine learning, this refers to the process of making decisions using a  model. Before the decisions can be made accurately, training must  occur.


 Light  below the frequency of (or with longer wavelength than) visible light. The  wavelength range is roughly from 800 nm to 1 mm. Near infrared is the range  near the visible part of the spectrum, from 800 nm to 2500 nm.

instruction set

Each  processor or processor family has a specific set of instructions that it can  execute. This is called the instruction set, or sometimes the instruction-set  architecture (ISA).


A  material through which electricity cannot readily flow. Plastic is a good,  familiar example.

intellectual property

This can  have lots of meanings, but, in the computer-chip world, it refers to parts of  a chip design that have been built and optimized by one company, which then  sells them to other companies that don’t want to design those blocks  themselves. They’re not selling actual chips; they’re selling the design of a  block that will be used within a chip.


The point  where two different domains meet, like a border. For example, a wall plug  could be thought of as the interface between the power grid and the  appliances you plug in.


When two  radio signals exist at the same frequency, you end up with a combination of  both. They are then said to be interfering with each other, meaning that they  mess each other up.

internet service provider

A  communications company that provides internet access to homes, phones,  or companies. For consumers, this could be the cable company, a phone company  offering DSL, or a cellular service provider.


This  refers to how well different pieces of equipment can work together. Macs and  PCs, for instance have some limited interop, but there are many Mac devices  that can’t work on a PC, and vice versa. This is an important notion for  systems, like the IoT, that involve many different pieces of equipment  working together


A  processor feature that lets some event interrupt the program that a processor  is running for a short time before returning the processor to the original  program. In and IoT device, it may wake the processor rather than  interrupting some other tasks.


The  Internet of Things. A broad term covering many different applications where “things”  are interconnected through the internet.


This can  mean two things (at least):

·          The Internet Protocol. Governs the addresses of  sources and destinations on a network (without worrying about what’s in  between). Used on Layer 3 of the stack.

·          “Intellectual property.” This can have lots  of meanings, but, in the computer-chip world, it refers to parts of a chip  design that have been built and optimized by one company, which then sells  them to other companies that don’t want to design those blocks themselves.  They’re not selling actual chips; they’re selling the design of a block that  will be used within a chip.

IP address

An  address used by the Internet Protocol (IP) to identify a machine on the  network.


A  network-layer security protocol. Largely used between gateways for traffic  traveling between (but not within) LANs. Not likely to be used within IoT  devices.


A band of  frequencies that anyone can use. In order to avoid interference, there are  rules as to how one can broadcast on this band so that everyone plays nice  together.


A number  used to encrypt (or encode) information so that no one can read it. Keys are  used when encoding and decoding. You shouldn’t have to mess with keys  yourself.


A  data-link-layer security protocol, largely used with Ethernet. This protects  data within a LAN only. It’s normally administered by IT professionals. Not  likely to be used within IoT devices.


This can  have various meanings, but in the context of a pipeline, it’s how long a  specific single task takes to get be completed.


The very  small amount of current that can flow through a transistor when it’s “off.”

legacy code

A  collection of software that’s been built up over the years. It’s usually been  improved an optimized gradually for the processor it’s running on, and it  works, so developers will be reluctant to make major changes to it.

load balancing

A way of  handling heavy server traffic by having multiple servers that can do the same  thing and then using another server as a dispatcher to assign tasks to the  least busy servers.


In our  context, a machine is anything that isn’t human (or living). That includes  electronic equipment like computers and phones.

Machine code

The  lowest-level representation of a computer program. It consists only of 1s and  0s, which a computer (or a machine) understands, but which is VERY hard for  humans to understand.

Machine language

This is  the lowest-level representation of a program – the 1s and 0s that the  processor sees and understands. It’s very hard for humans to read.

Machine learning

 Machine  learning (or ML) is a process by which machines can be trained to perform  tasks that required humans before. It’s based on analysis of lots of data,  and it might affect how some IoT devices work.

 Machine vision

 Technology  that gives machines the ability to see things and make decisions based on  what they see.


 A  data-link-layer security protocol, largely used with Ethernet. This protects  data within a LAN only. It’s normally administered by IT professionals. Not  likely to be used within home IoT devices.


A sensor  that detects magnetic fields — from the earth or from anywhere else.


Software  that usually finds its way into a computer or phone or IoT device without the  knowledge or approval of the device’s owner. It’s malware when the intended purpose of the software is to  cause some kind of harm.

Master key

A  security key used in some systems to create individual root keys for IoT  devices.


An array  of numbers, having both rows and columns of numbers. Widely used for many  complex tasks.

Memory address

When  referring to memory, a binary number that shows where, within some memory  block, the data you want is located. If you want to read or change that data,  you have to give the address so that the right data is read or changed.

Memory management unit

Circuitry  that keeps track of what’s been loaded from a hard drive into DRAM and  translates virtual addresses into physical addresses.


Small  programs that do things that, in an earlier time, would have been done within  one large program. Breaking them out into smaller programs that then act as  services to other programs makes them more robust and easier to maintain.


A  simplified representation of something real. We can create models of things  in our heads without even realizing we’re doing it. Technology often involves  models because they let us simplify what would otherwise be extremely  detailed, complicated concepts by focusing only on essential elements.


A piece  of network equipment that converts data into a format that can be  transmitted. Old modems sent the data on a phone line; modern cable modems  send the data across a cable connection. It stands for  “modulator/demodulator.”


This  generically refers to how some physical medium – like a wire or a radio  signal – is modified to carry data. It might be by moving the voltage up and  down, or it might be by changing frequencies of some periodic signal. There  are lots of ways of “coding” data so that it can travel across the medium.  It’s a really low-level detail; most of us don’t need to know any of the fine  print. The opposite of modulation is demodulation, and a piece of network  equipment that does both (modulation for sending, demodulation for receiving)  is called a “modem.”


A  lightweight transport protocol for Layer 4; may be more appropriate for IoT  equipment. A communications protocol designed for small systems such as those  used for the IoT.


In the  Cloud, this refers to a situation where multiple different users or systems  are sharing the same server. Ideally, those different “tenants” will never  affect each other. When a cloud server is used to host more than one set of  programs or users.


A means  of sending a message to multiple specific destinations (unlike broadcast,  which isn’t specific).


Describes  a computer chip that has more than one CPU on it.

Name server

A server  that’s part of the internet infrastructure. Its job is to take a website name  (like “” and return the IP address for that website. That  lets us use human-friendly names that then get turned into machine-friendly  addresses.


Circuits  done where an active transistor works barely above the threshold voltage.

Net neutrality

The  notion that an internet service provider needs to treat all traffic equally,  without giving preferential treatment to traffic from specific companies.


A  collection of items like computers, printers, phones, and other electronic  items that are connected together by switches and routers. A network allows  the connected devices to talk to each other electronically. The internet is  an example of an extremely large network. Your home network, if you have one,  is an example of a small local network. 

Neural network

A type of  conceptual network organized in a manner inspired by our evolving  understanding of how the brain works.


This  refers to systems that attempt to operate in the same way that the brain  operates. Spiking neural networks are the main commercial example.


In the  context of a thread, refers to threads that can go off and do their thing  without any other part of the program having to wait for them to finish.


When  talking about programs, these are “things” that can be created in a way that encapsulates  the details, letting them be accessed from outside through an interface. 

Object code

A program  that’s been assembled, compiled, or translated into machine code.

Object-oriented programming

 A  programming style where the programmer creates and manipulates objects to  achieve a goal.


 A base-8  counting system (rather than the base-10 system we usually use). Digits can  go from 0 to 7.


 This is  the process of connecting an IoT device for the first time. You connect to a  network, and then the device connects “home” for registration and for  confirming that the device is legitimate.


 This is  the process of connecting a new IoT device to the cloud for the first time.

Operating system

 Software  – or firmware – that handles the low-level aspects of a computer or IoT  device. It gets direct access to all the resources. Software asks the OS for  access to those resources.


The  direction someone or something is facing. This may be different from the  direction of motion.


 At right  angles (or 90°) to something else. More generally, two settings or properties  that you can set independently of each other are said to be orthogonal.

 OTA update

 A way of  updating IoT devices by sending a new software package wirelessly to the  device. But the concept is valid also for devices that aren’t updated  wirelessly.


A  substance created when oxygen binds to some other element. When that happens  with iron, we get rust. When that happens with silicon, we get materials like  sand and quartz. Often, the oxides of conductors and semiconductors will be  insulators. 


A group  of bits being sent from one place to another. How big the group is may vary  depending on what kind of packet it is. Long messages — like an email — will  typically be broken up into many packets, each of which travels independently  until it gets to the destination, where they’re reassembled into the email.


A chunk  of memory on a hard drive or SSD that can be brought into DRAM for use or for  execution.


The main  contents of a message. Using an analogy, when you receive a letter in the  mail, the letter itself is the payload; the envelope is merely a carrier.


 This can  be a characteristic of some signal. If the signal changes somehow, and that  change repeats itself exactly over time, over and over – like a sine wave –  then the signal is said to be periodic. The amount of time it takes for the  signal to repeat itself is called the “period.”


An event  that repeats itself repeatedly at some fixed rate or frequency.


 A way of  creating patterns on a silicon wafer for selective deposition or etching. You  can think of it as taking a picture of the pattern and having it show up on  the wafer. In the industry, photolithography is often  abbreviated as lithography.


 A piece  of glass with a pattern on it that is used to block light or let light pass  through in different places. Used for photolithography.

 physical address

 The  location of some item in physical memory.


A natural  phenomenon with certain materials where, if you stress them mechanically  (bend, for example), they exhibit an electrical change. The reverse also  occurs: if you apply an electric field, they will bend or deform in some way.  The effect is tiny, but measurable.


A way of  speeding up a repeated task by breaking it up into stages and having  different resources do each stage. It takes longer for the first task to be  completed (that’s the latency); the others come out in quick  succession after the first one.


A fourth  state of matter (the other three being solid, liquid, and gas). It’s  characterized by atoms being stripped of their electrons; it takes a lot of  energy to get into this state.


This word  can mean different things. It may mean a set of infrastructure on which  someone can build an IoT device or service. Or it could be a generic piece of  hardware that can be used for many different things.


A  variable that, instead of holding data, holds an address where data is  located. That is, it “points” to the data instead of being the data.


 Refers to  a processor that’s looking for something to happen, and it simply asks over  and over and over again whether it’s happened until it does happen.


The rate  of energy consumption. For electricity, it’s measured in watts (W).

printed circuit board

 Some kind  of board (usually rigid) that gets metal connections “printed” onto it.  Electronic components can then be soldered on.


 Refers to  whether or not information gathered about your usage of IoT devices by  authorized people can be made public, or shared with others, without your  consent. Different from (although related to) security, which protects such  data and devices from access by unauthorized people. Different from privacy,  which is more concerned about use of data by authorized people.

private key

 A key  that should be known only by your device and, possibly, by someone or  something else that your device is communicating with. It must be kept  secret.

 private key

 A key  that must be kept secret or else security will be blown.


 A  computer chip that does computing work for a computer. It may do general work  (like in your home computer) or it may do specialized work (like some of the  processors in your smartphone).


 An  agreed-upon definition of how some device works – what commands it can  receive – and what those commands should look like.


 An agreed  way of doing something. Like a convention, except that protocols tend to be  related to processes.


 This is a  manufacturing step where your IoT device gets its own private key. The key  and your device’s ID are likely stored in a database so that your device can  be recognized when you connect for the first time.


To take  data that has personally identifiable information and separate out or obscure  the link between the data and the individual. The link can still be made, so  it’s not anonymous, but it’s harder to make the link.

public key

 A key  that you (or your device) can publicly share with someone or something else.  This key can be used only to encode (or encrypt) data; it can’t be used to  read that data. Each public key has a matching private key, and the private  key is used for decoding (or decrypting) data. This lets you have a secure  conversation with someone or something that you’ve never shared keys with  before.

 public key

A key  that can be freely sent out in public, without being hidden. It works because  it’s paired with a separate private key that’s needed for reading a message  that was encrypted with the related public key.

 public/private  key infrastructure

A system  of mathematical algorithms for public and private keys as well as  certificates of authority that are used when authenticating a web session.


A way of  sending data to multiple destinations. The destinations subscribe to the data  using a broker; whatever is generating the data (possibly a sensor) publishes  the data to the broker; the broker either sends to the data to the  subscribers or lets the subscribers request data.

real time 

This is a  term that refers to computing or other processing that happens at the same  speed as something is actually happening. A familiar example might be  spell-check in your word processing program. In the old days, you did a  spell-check of the entire document after it was written. Modern programs do  spell-check “in real time” – that is, right as you type, it’s checking; no  waiting until the end and doing the whole document at once. Doing something  in real time is often a good thing, but it means you have to do whatever  you’re doing fast enough to keep up.

real-time operating system

An OS  where various tasks can be guaranteed to be completed within a specific  timeframe.


In the  context of machine vision, a task that identifies not just what kind of thing  is in the image, but which specific individual it is.


The  process of eliminating or transforming the negative parts of an AC signal or  power.


One way  machines can communicate, where one machine sends a request (or issues a  command) to another machine; that other machine responds with data or maybe  with an acknowledgment to a command.


Forces  that tend to reduce the amount of flow or current. Measured in ohms (Ω).


A way of  programming that has evolved out of web programming, and it’s more abstract  than other older languages like C.


 Reduced  Instruction Set Computer; a kind of processor that has far fewer instructions  than a CISC processor. It can still do the same things, but it may require  the use of multiple simpler instructions instead of one complicated  instruction.


 A type of  artificial neural network used for analysing streaming input like speech or  handwriting.


 When  talking about software updates, this refers to a situation where a new update  fails, and you want to revert to the old version.

 Root key

 A key  that is typically unique to each IoT device (but might not be) and which is  used to create session keys for communication between IoT devices and IoT  servers in the cloud.


 An  electronic box that helps steer data on a network. For instance, you may have  one in your home connecting your phone and computer and other devices to each  other and to the internet. The data itself has information about where it’s  being sent; the router uses that information to send it in the right  direction. At a really basic level, you can think of a router and a switch as  being the same thing. If you want to get more technical, a switch creates a  local subnetwork, and the router connects multiple subnetworks (or multiple  networks).


Refers to  whether IoT devices or data are protected from unauthorized viewers.


A  material that, under some circumstances, can conduct electricity and, in  other circumstances, cannot.


 A device  that can measure something about its environment. Examples are movement,  light, color, moisture, pressure, and many more.

sensor fusion

 The  process of combining information from multiple sensors (real or virtual) in  order either to give more confidence in a result or to come up with something  completely new.


 A  computer with a dedicated purpose. Older familiar examples are print servers  (a computer that controls local printing) and file servers (a computer used  for storing files centrally). More modern examples are web servers (the  computers that handle your web requests when you use your browser) or  application servers (computers dedicated to handling the computing needs of a  specific application). Servers are often powerful, expensive machines since  they have to handle a heavy load.


We are  used to purchasing products outright. “Services” is a new concept where you  may or may not buy the product, but optional or mandatory services come with  the product. Those services may have an ongoing cost separate from the  purchase price.

session key

A  one-time-use security key used for encryption during a single communication  session between an IoT device and an IoT server.


An  element (number 14 in the periodic table) that can be a semiconductor, making  it the material of preference for circuits and micro-mechanical devices.


The state  of a machine whereas many non-essential electronic elements as possible are  shut down, without powering the machine completely down.

smart city

A general  name for cities that use technology to make things work better for residents,  workers, and visitors.

smart home

A  buzzword for interconnected home devices – TV, refrigerator, door locks, etc.


In this  context, “software” refers to functions in an IoT device that are implemented  by running instructions through some kind of processor. It’s distinct from  “hardware,” where functions are built into a silicon chip or some other  component.

source code

A program  that’s readable by a human, usually in a high-level language.


An  analysis tool that measures how something responds to different frequencies  (or colors) of light. Those colors might not be visible to humans – like  infrared or ultraviolet.


A range  of frequencies. A prism shows a range, or spectrum, of visible light  frequencies (yes, light is a wave). This is the literal definition of  spectrum. Other uses – like references to the autism spectrum use  the word figuratively to indicate a continuous range. In our context, this  refers to the range of radio frequencies available for communication. Access  to those frequencies is usually regulated by governments since they’re viewed  as a public asset.


 Done by a  processor, it means that the processor has to guess ahead of time what the  result of a test will be so that it can load those instructions into the  pipeline. If it’s wrong, it will have to empty the pipeline and restart with  the correct instructions.

spiking neural network

An  approach to neuromorphic machine learning that attempts to mimic how the  brain (or parts of the brain) works.


Stands  for “static random-access memory.” This is also temporary memory in a  computer. It’s very fast compared to other kinds of memory, but it’s also  very expensive and burns a lot of energy, so you don’t have nearly so much.


A memory  that acts like a hard drive, but is built out of flash memory instead.


Secure  Sockets Layer. A common internet security protocol. TLS is a more recent  version of this, but SSL is still used. Works with TCP on Layer 4 of the  stack.


Related  to communications: A way of organizing parts of a complicated process (like  communications) so that any task relies on tasks below it and feeds the tasks  above it.

Related  to computing:
A place  in memory where you store “where was I?” information when you go from, say,  one function into another. Before starting a new function, you store where  you were in the old one so that, when the new function ends and you’re back  in the old one, you can figure out where you were and continue.


Ideally,  a CPU executes instruction after instruction, with no breaks. But there are  times when there may be a delay – getting new data from DRAM or having to  reload the pipeline due to a branch, for example. When this happens, we say  that the system briefly “stalled.”


A way of  doing something specific that has been agreed by multiple parties in an  official manner. Some “standards” aren’t official standards; the best ones  have been established in an open fashion, where anyone with an interest can  contribute and where large companies can’t push little companies around.

standards body

A group  of companies getting together in a manner consistent with anti-trust laws to  agree on how to do things. Rather than limiting competition, this is intended  to foster competition by getting agreement on some basic thing (like wall  sockets having 110 V) and then letting companies compete on that basis.


A broad  term that can apply to a lot of systems. Let’s say you have a system that can  be one of two ways – on or off. That “on-ness” or “off-ness” is the state of  the system. The system is either in an on state or an off state. Many  different kinds of systems can have many different kinds of state. There are  many complex branches of engineering or physics or even mathematics that deal  with state. The easiest way to think of any of them is, “the way things are”  (which may depend on the history of prior states, meaning how they got to  this particular state).

static power

The rate  of energy consumption of a circuit when nothing is switching — it’s just  sitting idle.


This  usually refers to memory that doesn’t lose its contents when powered off –  like a thumb drive or a hard disk. It’s a place to store data.


Circuits  done where an active transistor works below the threshold voltage. 


A portion  of a bigger network. For example, if you have a home network and it’s  connected to the internet, then your home network is a part of the overall  internet network. That home part is therefore a subnetwork. Any  self-contained subset of a bigger network can be called a subnetwork.


A small  portion of a program that’s set aside and given a name. It helps isolate key  code in an easy-to-understand way, and it makes changes easier and less error  prone. It’s a really important way to make programs easier to understand. May  also be called a function.


Circuits  done where an active transistor works at voltages well above the threshold  voltage


A type of  capacitor that can be used for storing energy.

supervised learning

A machine  learning approach where a machine is trained by giving it examples and,  during the training, telling the machine what the answers are. A large number  of varied examples provide the best results.


A switch  helps direct network traffic to the right destination. At a high level, it’s  very similar to a router. Technically, switches are used to create local  subnetworks; routers connect subnetworks together.

symmetric key

 A way of  encrypting data that uses the same key both for encrypting and decrypting.


This is a  very generic term for any collection of components that, all together, can do  something. Systems can be built from subsystems. Examples are your cell  phone; your computer; the radio in your car; anything that seems like a  “whole.”

system of systems

A system  built out of other smaller systems. Just as you might say that a system could  be built out of subsystems, you can also say that separate systems can be  combined to create a larger system. They’re just different ways of saying the  same thing.


Transmission  Control Protocol. A more reliable way to set up connections that might have  two-way traffic or need better guarantees that messages get delivered. Used  on Layer 4 of the stack.


Pronounced  “TCPIP” or “TCP over IP.” A common configuration where TCP is used on Layer 4  and IP is used on Layer 3.


 Measuring  information about communications. For the IoT, it could be things like how  and when things are communicated, how much is communicated, etc.

 The cloud

A generic  phrase referring to large numbers of computers located somewhere far away and  accessed over the internet. For the IoT, computing may be local, done in the  same system or building, or in the cloud, with data shipped up to the cloud  and then the result shipped back down.

the fog

Refers to  some way of doing “cloud”-style computing without having to use the cloud. A  local server (or router or something else) can act like the cloud; because  it’s local, it’s referred to informally as the fog.


A sensor  that measures temperature.


A piece  of a program that can execute at the same time that some other piece of that  same program can execute.

threshold voltage

The  voltage at which a transistor starts to turn on. It’s technically “off” below  that voltage, although it is still ever so slightly on.


Transport  Layer Security. A very common internet security protocol. You can think of it  as an updated version of SSL, although both are still used. Used with TCP on  Layer 4 of the stack.


Refers to  any kind of electronic message — email, web page request, streaming  video, or anything else — that travels over a network.


With  machine learning, a model must be trained in order to perform its function  (which is called inference).


A device  that converts one kind of energy, like the energy of motion, into another,  like the energy of an electric current. Transducers are fundamental to  sensors, since they let us measure something physical as an electric current.

trusted  execution environment

A  separate area inside a processor where trusted software can run, with access  to all resources. Software running outside that area has to access resources  through the trusted area; it can’t do so directly.


 A  phenomenon where current can flow through a very thin insulator due to  quantum effects.


User  Datagram Protocol. A “best effort” (i.e., no guarantees) way to get a message  from one place to another. Used on Layer 4 of the stack.


Sending a  message to one single destination.


The  modern way of representing worldwide characters in computers. It covers all  existing scripts and then some. It replaced ASCII.

unsupervised learning

A machine  learning approach where a machine is trained by learning as it goes. It  doesn’t get trained by examples ahead of time, and isn’t explicitly taught  the “right answers.” There must be some other way of reinforcing the right  and wrong answers as it learns.

user interface

This is  an interface between something and the user of that thing. In a car, the  pedals and steering wheel are all part of the user interface. You’re probably  more familiar with the user interface (or UI) on a computer. If that  interface involves graphics, then it’s a graphic user interface,  or GUI (pronounced “gooey”).


A one-row  matrix that can have any number of columns.


In our  context, refers to what are usually software models of some physical thing.  The model behaves like the real thing except, in some cases, in performance.

virtual address

The  location of some item as generated by a compiler. In more complex systems, it  will likely need to be translated to a physical address by an MMU before it  can be used.

virtual machine

A way of  configuring a portion of a real-world computer to look and act like a  complete computer on its own. The idea is to have multiple virtual machines  on a single real machine.

virtual memory 

A scheme  for translating virtual addresses, created by a compiler, into the physical  addresses representing where things are located in a real system.

virtual sensor

A source  of data that, strictly speaking, isn’t a sensor, but that can be used as if  it were a sensor.


Voltage  is what gets electrons to flow. It’s analogous to water pressure, which gets  water to flow. Voltage is measured in units of “volts.”


In the  context of making circuits, sensors, and actuators, a thin, round slice of  pure silicon. Multiple devices will be made on it; it will then be sliced up  to separate the individual chips.

 wake word

 For  personal assistants like the Amazon Echo, this is a word or phrase that the  device listens for. When it hears it, it knows (or thinks) that you’re going  to give it a command.

walled garden

An  approach to the IoT that restricts which devices and brands you can have work  together. It could protect you, help assure interoperability, keep out  certain competitors, or any and all of the above.


Wide-area  network. This is  a broad description of the core networks that connect different LANs together  around the world. When traffic leaves a building, it usually goes through a  gateway out onto the WAN before returning elsewhere through a different  gateway into a different LAN. You could think of this as the internet.

web server

A server  whose purpose is to receive requests for web pages and then send those pages  out to the requestor.


 A common  type of wireless network used to connect computers and phones to each other  and the internet.

wireless power

Technology  that allows a battery to be charged from a small or large distance, over the  air, without having to connect a charger.

word line

A line in  a memory that selects which word (and its associated bit cells) will be  selected for reading or writing, based on the memory address. The word lines  and bit lines are orthogonal to each other, making an array of the bit cells  that connect them.


A fusion of IPv6 (the current Internet  protocol), and Low-Power Wireless Personal Area Networks, it permits  power-constrained IoT devices to access the TCP/IP Internet directly. This  means that even the smallest and weakest IoT devices can have connectivity.

Advanced  Encryption Standards

 This is an electronic data encryption  specification that has been the standard for IoT device transport layer  security since 2001.

Bluetooth  Low Energy

 A wireless, personal-area network  characterized by lower power usage and a limited range for data transmission.  It’s also called Bluetooth 4.0.

Embedded  Software

 The computer software that controls hardware  devices and systems that are not usually considered computers, like a smart  refrigerator, for instance.


Also known as FOTA, this  technology allows the remote wireless installation, repair, and upgrading of  software and services on mobile devices.

Global  Navigation Satellite System

The GNSS is any satellite navigation system that  offers autonomous geo-spatial positioning, timing, and navigation, either by  region or globally.

Link  Budget

This is a telecommunication system jargon  that describes an accounting of all of the gains and losses going from a  transmitter, passing through the medium, and ending up at the receiver.

Low-Power  Wide-Area

A network offering a low range and low power  consumption, used primarily for M2M communications

Low-Power  Wireless Sensor Network

A collection of scattered, independent  devices that measure environmental or physical conditions, all without  significant power consumption.

Lora  Protocol

A long-range digital wireless communication technique to  facilitate IoT and M2M communications.


A more power-efficient standard for machine communications.

Media  Access Control

A data link layer (DLL) sublayer transmits data packets to  and from a network interface card.

Mesh  Network

A network system where devices transmit their data while  also serving as relays to other nodes.

Mobile  IoT

Low power, wide area devices used in conjunction with  mobile devices interfacing with IoT networks.


This stands for Narrow Band IoT and is used as a  convenient, cost-effective means of expanding IoT into a whole new series of  devices and everyday household items. This is a low-power, wide-area  technology, and will be instrumental in increasing the scope of IoT in the  years to come.

Near-Field  Communication

Otherwise known as NFC, it permits two-way communication  between closely located endpoints. It’s a short-range, low-power, low-speed  form of radio communication.

Quality  of Service

A measurement of how well a network supports IT  connectivity. This covers elements such as transmission delays, availability  of connections, and data loss.

Radio  Frequency Identification

Commonly called RFID tags, uses electromagnetic coupling  and radio frequencies to identify people and things. It has a limited range  and data transmission capabilities. The number bibs that runners use in road  races, for instance, are equipped with RFID tags to confirm they passed  certain course checkpoints.

RF  Geolocation

Otherwise known as using a radio transceiver to find  another radio transceiver. The classic example of this is the ever-popular  GPS, found in many models of cars.


A device used to extend network range by receiving a  digital signal and re-transmitting it.

Sensor/Sensor  Network

A device or group of devices that monitor and collect  environmental data from a variety of locations in network range.

Smart  Meter

A device used by utility companies to collect information  about energy consumption (e.g., electricity, natural gas, water), and  transmit the data back to the company or even to the consumer.

Software-Defined  Network

 A network method that reassigns information flow control  from hardware in favor of a software controller.


A computer system designed for long-distance data  transmissions, the most ubiquitous example being GPS and satellite radio tech  installed in automobiles.

Transmission  Control Protocol/Internet Protocol

Better known as TCP/IP, this is the basic protocol suite  for all Internet and private network communications and connections.

Ultra-Wide  Band

 The UWB is a weak signal sent over a wide frequency and is  employed mostly as a localizing signal and distance measurement.


 Devices were worn by people and equipped with sensors,  monitors, and an Internet connection to gather data regarding the wearer’s  activity, life, and environment (e.g., Apple Watch, Fitbit).


 Used for personal-area networks (PAN), this is a  short-range, low-power standard employed for control and sensing, and can  also be used to create a more extended range, energy-efficient, low data  transfer rate networks.