The purpose of this glossary is to help understand terms used in my writings. It is not complete and the definitions are not formal. I plan to put a pointer to a "full service" technical dictionary here when I find one that is suitable. Please send me suggestions as well as comments on the definitions. I assembled this glossary in the 1990's and is not actively maintained so some definitions may be are stale.

Other sources include:


This is a collaborative effort and my preferred reference for these definitions

The Jargon File. his is also known as the Hacker's Dictionary. A site rich in definitions and hyperlinks.

Internet Documents are archived at the IETF but better versions are at For convenience some definitions groups (a new feature so only new groups are included_

1xRTT A protocol for sending data packets of a CDMA network. Supports speeds up to 144 Kbps. This is part of a family of so-called 2.5G (G for Generation) protocols. GPRS is a similar protocol for GSM systems.
802.11 and Wi-Fi Popular radio protocols. Typically used as a transport for Internet Packets (IP). Think of it as simply being part of the Internet
ARPANET The Advanced Research Protects Agency Network. This was the precursor to the Internet and established the viability of packet networking. While the Internet itself directly evolved from the ARPANET, the Internet represents a fundamentally different philosophy in that the transport level (the IP protocol) is decoupled from the application protocols such as TCP and UDP.
BIOS Originally stood for "Basic IO System". In practice it is the code that is built into a system, especially a PC, that provides very low level services and handles the initial system start it. It takes control when the system is powered up. In more recent PC operating systems, many of the functions are taken over the the OS itself.
Bluetooth Seemingly similar to 802.11 but very different in practice. The least important difference is that it uses a different kind of radio but the real difference is that the term "Bluetooth" applies to both the radio and the application protocols. Thus it is not a flexible substrate and thus it gives you the answers rather than asking what you might want to do. We work around some of this but ultimately it's limited by its design.
CDMA Code Division Multiple Access. This is a more sophisticated approached based on spread spectrum (frequency hopping this case). It also demonstrated the viability of spread spectrum even though the technology itself had been around for a long time. 802.11 and Bluetooth uses flavors of spread spectrum
Cellular Telephony The name comes from the innovation of using overlap "cells". In the analog (AMPS) version each phone had an assigned channel. Because of the accidental properties of FM (Frequency Modulation) each tower would only pick up the strongest signal. Thus you could increase the capacity of the network by adding antennas (or towers) and support many two-radios. This allowed the creation of cellular telephone. Today we use digital systems and more effective protocols but the idea of using cells still defines the business. See related terms.
CEBus Consumer Electronics Bus. An ambitious attempt to create a protocol for home control. Unfortunately, it exhibits the fundamental flaws of creating a world unto itself and shows little understanding of the world the of IP Infrastructure.
DSL Digital Subscriber Line. A general term for technologies that use digital signaling to send data over existing phone lines without affect "normal" telephone calls. Specific forms include:
  • ADSL. Asynchronous DSL, usually high speed from the central office to the subscriber and lower speed for the return path.
  • SDSL. Symmetric DSL
  • ISDL. Actually ISDN DSL, a form of ISDN with different gear at the central office
  • CDSL, or UAWG or G.Lite. Consumer DSL which doesn't require a splitter. The signal is decoded in by a DSL modem.
DSL technologies use the wire from the central office to the home. See HomePNA for in-home technologies.
DNS Domain Name System. This is the system used for names such as Joe.Smith.Com or London.Gov.UK. Each name is registered with the next higher level name. In this case, Smith is registered under Com. The a DNS entry can contain various "records" of information such as the IP address or how to route mail to a given system. The DNS is just a registry and says nothing about the actual location of the host or entity that is named. See RFC-1034.
Domain Name A Domain Name is simply a name registered in the DNS. In some case can one use an actual IP address as in sending email to user@[].
End-to-End Argument See The End-to-End Argument for a full discussion. Very simple put, what matters is whether information is exchanged between communication applications. Reliability at the network level doesn't guarantee end to end integrity. Thus the applications must take this responsibility. At best, network reliability adds efficiency. At worst, it interferes with the applications by imposing unnecessary performance requirements.
EV-DO Part of a family of so-called 3G mobile technologies. Other flavors are UMTS and EDGE (2.75G?). Currently deployed by Verizon in the United States as an upgrade for 1xRTT.
Firewall This is a device (or program) that is meant to protect a local network from the rest of the Internet. See my comparison with the Maginot line for a more complete discussion.
Firewire Now called IEEE-1394.
Fungible This is a term from accounting that means interchangeable. When you buy corn or salt you don't care which grains you get, just how many. The same is true for bits -- the bits themselves have no special meaning. There are no Verizon bits nor SBC bits. This is the essential problem that the carriers face " since the bits have loyalty the carriers must assure the bits rid their channels and it is not in their nature to stay confined.
Gordon Moore A founder of Intel best known for Moore's law.
GSM Global System for Mobile communications (the actual words are French since that's a tradition for such acronyms). It is a digital system introduced in Europe in 1991. The design associated the service with a SIM card rather than the hone itself.
HomePNA See the A set of technologies that allow existing phone wire within the home to be used for networking. The other created the initial version this technology working with Tut Systems. Newer, higher speed versions were created by Epigram. The technologies can coexist and interoperate.
Host Name A Domain Name associated with a given computer system (or set of systems). Typically used in a mail address as in User@Host.
HTML Hypertext Markup Language. It is the basic way to markup a page for the World Wide Web. For example, <b>is used to indicate bold face.</b>. The ability to create it directly without special tools has been an important factor in its widespread use and in the ability extend it.
HTTP Hypertext Transport Protocol. The protocol that is used to exchange HTML between systems. It is of interest only to the very technical.
IEEE-1394 (Also called Firewire) Protocol for high speed connectivity home entertainment and other audiovisual devices. Sony and Apple a prime sponsors. Unfortunately all the assumptions about the protocol are built into the physical layer. You can see the SkipStone site for more information.
IETF Internet Engineering Task Force. Quoting from their site: "The Internet Engineering Task Force (IETF) is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet."
the Internet This is the term for the collection of local networks and their interconnection using the Internet Protocol (IP). Unfortunately the term has become popularized and is often confused with the Web and other applications. To avoid confusion, I will often refer to the "IP Infrastructure".
the Internet Protocol See IP.
IP Internet Protocol. This is the "low level" protocol used to transport messages on the Internet.
IP Intellectual Property. Don't confuse the two uses of the acronym
IP Information Provider. Less common but another use of these initials.
IP Infrastructure This is a term I prefer to the Internet in order focus on the underlying technology rather than the applications that use this infrastructure. It is the layer below protocols such as TCP.
IPSEC IP Security Protocol. More details.
IPV4 Version 4 of IP has been the primary protocol in use since the 1970's. Unfortunately, there was a major failure of imagination and only 32 bits were set aside for the address. This leaves a limit of 4 billion addresses which is too small for the number devices we can expect on the net in the next few years. The problem is exacerbated by the need to preallocate large numbers of addresses for network management and routing purposes.
IPV6 The main advantage of IP Version 6 over Version 4 is in the expansion of the address from 32 to 128 bits. With this large an address, not only are there enough addresses for many more devices, it is also easier to move devices since the routing information can be readily updated. The IPV6 Organization is focused on support V6 deployment.
IR Infra-Red. Used like RF for communications but limited to line-of-sight.
IrDA The Infrared Data Association. General used for protocols defined by this organization. Unfortunately IrDA protocols tend to be smart and focus on the data transport rather than enabling general connectivity. There are, however, IP over IR implementations available for connecting systems.
Layer Layers are traditional way of describing protocols. The Internet inverts this paradigm by decoupling the applications from how we exhange bits. This is an insight I had since first writing this glossary over ten years ago and has not yet been integrated into the definitions.
MIME Multipurpose Internet Mail Extensions. This is the protocol used to extend the preexisting text-only email system so that it could be used to carry messages with formatting, images, multimedia etc.
Moore's Law Based on Gordon Moore's observation that the price of semiconductors halved every 18 months. It's a bit of a cheat in that he used that rule to set Intel's prices. More generally the term is used for any example of prices of hardware dropping rapidly due to rapid development and innovation. See Intel's description for more details.
Modding Modifying electronic games. Also used for hacking PC hardware for those who value form as well as function.
MPEG Moving Picture Expert Group. Standards body creating compression technologies.
MPEG-2 Standard for compressing video or television. See MPEG-2.
MPEG-3 There is no MPEG-3, MPEG-4 is the next in the series. This left a vacuum so filled by using it as a synonym for MP3.
MP3 Formally, MPEG-2 Layer III; an audio compression standard that has become the focus for making music available on the Internet. Sometimes incorrectly called MPEG-3. Corrected entry thanks to Charles Poynton
No New Wires A term I started using for networking approaches that take advantage of existing wires (such as phone wires) or no wires (wireless). These approaches are aimed at enabling networking without a large upfront investment. HomePNA is a phone-wire implementation.
PC In the context of these essays, it stands for personal computer. The usage is ambiguous. It usually refers to any personal computers including those from Apple. Sometimes it is used to differentiate "IBM compatible" systems from Apple systems.
PSTN Public Switched Phone Network. The legacy phone network that your grandparents knew. Highly tuned for voice traffic and patched to support fax and tolerate modems.
RF Radio Frequency. Generally used for wireless communications. Also see IR. It's really just a mathematical construct that the naive confuse and treat as if it were a real resource thus creating a scarcity and thwarting free speech. Used in what I now call Single Frequency Shouting
RFC Request For Comments. This is the main series of memos on Internet architecture and protocols. They started out as memos for discussion and the series title helps preserve the atmosphere of open technical discussion. You can find documents in the RFC Archive. Also see STD1.TXT for the current list of standards. ZVon has the doucments with better formatting
the Regulatorium A term I coined to refer to the system of regulations centered on the FCC. We need a term so that we can talk about the whole ball of wax rather than finding ourselves engulfed in it arguing within it's laws. The Regulatorium has become a reality unto itself detached from the real world.
SCSI Small Computer Systems Interface. This is a standard for connecting external devices, such as disk driver and scanners to a PC. It has evolved over the years to allow fairly high speed connections.
SMTP Simple Mail Transfer Protocol. This a very simple protocol for transferring mail. So simple that one can send mail just by connecting to the SMTP port on a machine and typing the message. See RFC-821 or RFC-821 (ZVON). for the specification.
Spam A term for unsolicited email, typically sent to large distribution lists. It is like paper "junk" or bulk mail. The main difference is that since the cost is so low it tends to contain really stupid offers though not always. But the reputation tends to taint even potentially interesting information. The term derives from Hormel's Spiced Ham product via Monty Python's generalization of the term.
TCP Transmission Control Protocol. This is a standard protocol to provide a reliable data connection over the IP transport. While using TCP simplifies many applications, it doesn't guarantee end to end reliability since there may be other kinds of failures. Often UDP is the preferred protocol.
Tellywood Television and Hollywood are essentially the same industry these days.
TLA Three Letter Acronym
URL Universal Resource Locator on the World Wide Web. See the W3C site for more detailed information.
UDP User Datagram Protocol. A simple protocol for sending packets over the Internet. There is no guarantee of delivery and no relationships between packets. Since this reflects the nature of the IP transport itself, UDP allows the application to define its own form of reliability without incurring the assumptions and inherent overhead associated with TCP. When sending audio, for example, there is no value in late delivery but there is the cost of the delays.
UUCP Unix to Unix Copy Protocol. The protocol used to transport email (and other files) between Unix system. Originally mail would traverse many intermediate systems on its way to its destination. Most UUCP addresses no conform to the domain naming conventions.
Virus A term for computer programs that can "infect" a system by installing themselves into the operating system or attaching themselves to programs. They then repeat the process on other systems. Unfortunately the term has become overused to the point of being applied to anything bad.
VisiCalc The first electronic spreadsheet. Look here for more details.
VoIP Voice over IP. A general term for technologies that send voice conversations over the Internet. Often used for specific technologies and services. Jeff Pulver is a good source of expertise on VoIP.
Wi-Fi See 802.11.
X-10 A product line and a 1970's vintage protocol for "home control". See for more details. It's advantage is that it is very simple. It's disadvantage is that it is very slow and unreliable.
X.400 International Standard for Electronic Mail. Though supported internationally by essentially all the governments and telecommunications companies it failed of its own weight against the trivially simply SMTP standard.
XML Extended Markup Language. Meant as a successor and/or extension to HTML. Allows more extensive description of data beyond how it should look on the screen. Is the basis for exchanging data between programs rather than just displaying it for humans.