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Acronyms:

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A B C D E F G H I JK L M N O PQ R S T U V W XYZ

100BASE-FX	A variant of IEEE 802.3 for a 100Mbps Ethernet-like network. Borrows the physical characteristics of FDDI's multimode fiber PMD, but uses Ethernet framing & CSMA/CD. One of three flavours of "100BASE-T" proposed by the Fast Ethernet Alliance. Came from the 100BASE-X proposal.
100BASE-T	Generic name for the 100Mbps variants of IEEE 802.3, especially the twisted-pair based ones. The three variants are called 100BASE-TX, 100BASE-FX, and 100BASE-T4. A medium-independent interface and an adapter is define (to be used like the AUI and MAU of 10Mbps 802.3). When a device is said to support 100BASE-T, usually 100BASE-TX is meant.
100BASE-T4	A variant of IEEE 802.3 for a 100Mbps Ethernet-like network. One of the flavours of "100BASE-T". Uses 8B6T encoding and 25MHZ clocking, and in addition to the two pairs traditionally used in the manner of 10BASE-T, also has two pair used in bi-directional half-duplex fashion. Among other things, this means that this particular kind of Ethernet cannot be made full duplex without the use of more pair. Came from the 4T+ proposal.
100BASE-TX	A variant of IEEE 802.3 for a 100Mbps Ethernet-like network. Borrows the physical characteristics of FDDI's TP-PMD, TP-PMD, but uses Ethernet framing & CSMA/CD. One of three flavours of "100BASE-T" proposed by the Fast Ethernet Alliance. Came from the 100BASE-X proposal.
100BASE-X	The old name for 100BASE-FX and 100BASE-TX.
100Mbps Copper UNI	ATM Forum UNI specification for 100Mbps over some sort of copper cable. I believe it is just 100MbpsUNI making use of FDDI's TP-PMD rather than the older fibre PMD.
100Mbps UNI	ATM Forum 100Mbps multimode fibre private UNI. Same as Fore's TAXI. Borrows optical characteristics & basic encoding of FDDI.
100VG-AnyLAN	Originally a proposal to IEEE 802.3 for a 100Mbps Ethernet-like network, later relegated to IEEE 802.12. Formerly known as 100BASE-VG. Uses Demand Priority media access method and Quartet Signalling. I've also seen reference to its ability to use Category 4 UTP, Category 5 UTP, and STP, but I don't know how many pairs.
100VGF	AnyLAN Forum, A group of vendors trying to accelerate 100VG-AnyLAN acceptance & interoperability.
10BASE2	IEEE 802.3 10BASE2: IEEE's standardised version of Digital Equipment Corporation's ThinWire Ethernet, which runs over a thinner coaxial cable than the original 10BASE5. Another old nickname for it was "Cheaper-Net". The coaxial cable is specific to 10BASE2, but two variants of off-the-shelf RG cable are sometimes used. The cable looks very similar to the cable used for IBM 3270-style terminals or that used for home cable TV, but has different electrical characteristics. The "2" in the name refers to the 200 meter (or more precisely, 185 meter) limit on thet cable length. Like 10BASE5, computers are attached along the length of the cable.
10BASE5	IEEE 802.3 10BASE5: "Ethernet" or "ThickWire Ethernet", IEEE's standardised version of the original 10Mbps Ethernet which runs over a rather thick Ethernet-specific type of coaxial cable. The "5" in the name refers to the 500 meter maximum cable length. Computers are attached along the length of the cable. See "Error! Bookmark not defined.".
10BASE-F	Three variants of IEEE 802.3 which runs over multimode fibre. See 10BASE-FB, 10BASE-FP, and 10BASE-FL and "Error! Bookmark not defined.".
10BASE-FB	IEEE 802.3 10BASE-FB: "Synchronous Ethernet" which is a special-purpose multimode fibre link for linking repeaters that allows the repeaters to communicate more efficiently, thus enlarging the count of repeaters that can be placed in series above the traditional 4. Described in IEEE 802.3 Section 17.
10BASE-FL	IEEE 802.3 10BASE-FL: multimode fibre Ethernet used to attach a pair of devices (each being either a host or a repeater) as a "Link Segment"--a lot like 10BASE-T except that it uses fibre. It makes FOIRL obsolete. 10BASE-FL transceivers can interoperate with FOIRL transceivers. It is described in IEEE 802.3 Section 18.
10BASE-FP	IEEE 802.3 10BASE-FP: passive star fibre Ethernet. Attaches a number of Ethernet devices together with a passive star hub (i.e., the hub is not electronic--it just splits the light travelling through each incoming fibre to go out all the outgoing fibers). It is described in IEEE 802.3 Section 16.
10BASE-T	A variant of IEEE 802.3 which allows stations to be attached via twisted-pair cable.
4T+	Old name for 100BASE-T4.
802, 802.x	see IEEE 802, IEEE 802.x.

AAL	ATM Adaptation Layer (ATM term) the layer between ATM cells and the (typically packetized) data that they carry. For example, if you send IP packets over an ATM network, some sort of ATM Adaptation Layer will be used.
ABR	Available Bit Rate (ATM term) one of several quality-of-service traffic classes used in ATM. ABR basically means "use whatever is available", i.e. don't offer any special quality of service.
ADSL	Asymmetric Digital Subscriber Line, modems attached to twisted pair copper wiring that transmit from 1.5 MBPS to 9 MBPS downstream (to the subscriber) and from 16 KBPS to 800 KBPS upstream, depending on line distance. Remote access method that makes use of a faster channel for local-to-remote communications than remote-to-local.
ANI	Automated Number Identification, a system used by the phone co. to identify a caller's phone number. * Codes do not block ANI requests. Calling a local ANI line will report the number of the phone being used.
ANSI	American National Standards Institute, a definer of standards of all kinds, including FDDI.
APON	ATM Passive Optical Network, a passive optical network running ATM.
ASP	Active Server Page, Microsoft’s mark-up language for Web Servers.
ASCII	American Standard Code for Information Interchange, the charater set used on almost all destops.
ATM	Asynchronous Transfer Mode, a method for switching little fixed-size packets (cells) around. Like T1 and DS3, digitised voice was a major consideration in its design, but it can be used for data. It can be run at different speeds over different media including T1 and DS3 as well as 51Mbps, 100Mbps, 155Mbps and 622Mbps standards (see SONET & TAXI). The fixed cell size is 53 bytes. Though ATM is really designed for voice and WAN, there are schemes to use it in LANs. ATM is a big buzzword these days but it is still very new, ultra high speed cell based data transmission protocol which may be run over ADSL.
ATM25	ATM Forum defined 25.6Mbit/s cell based user interface based on IBM token ring network.
ATU-C and ATU-R	ADSL Transmission Unit, Central or Remote, the device at the end of an ADSL line that stands between the line and the first item of equipment in the subscriber premises or telephone switch. It may be integrated within an access node.
AUI	Attachment Unit Interface, the Ethernet/IEEE 802.3 term for the interface between a MAU and a station. A special kind of cable known as an "AUI Cable" can attach a MAU to a station at a distance (up to 50 meters).
AVI	Audio Video Interleave, a graphics file format extension

BDSL	Same as VDSL.
B-ISDN	Broadband Integrated Digital Network, a digital network with ATM switching operating at data rates in excess of 1.544 or 2.048 MBPS. ATM enables transport and switching of voice, data, image, and video over the same infrastructure.
BNC	Bayonet Neill-Concelman, a type of connector, a type of connector used for attaching coax cable to electronic equipment which can be attached or detached quicker than connectors that screw. ThinWire Ethernet (IEEE 802.3 10BASE2) uses BNC connectors.
BBS	Bulletin Board System, a BBS is a computer service where users can chat, post messages, download files, etc. Most BBS's are dial-in. While very popular in the 1980s, the advent of the internet has led to their gradual extinction.

CAT 3	Category 3 Unshielded Twisted Pair standardisation of unshielded twisted pair cable for voice use. Some data communications standards such as 10BASE-T can utilise it.
CAT 4	Category 4 unshielded Twisted Pair standardisation of unshielded twisted pair cable.
CAT 5	Category 5 unshielded Twisted Pair standardisation of unshielded twisted pair cable for data use. TP-PMD requires Category 5 cable rather than Category 3. h
CAT 6	Category 6 Name people and organisations often associate with their various proposals for yet another grade of twisted pair media. At the time of this writing, 9/27/97, there is no official "Category 6".
CATV	Community Access Television, also known as Cable TV..
CBR	Constant Bit Rate, an (ATM term) one of several quality-of-service traffic classes used in ATM.
CCITT	Consultative Committee for International Telegraph and Telephone, an international telecommunications standards organisation, now subsumed by the ITU.
CDDI	Copper Data Distribution Interface, Commonly used term for TP-PMD, but actually a trade name of Crescendo.
CGI	Common Gateway Interface, a protocol that allows for communication between a program and forms on the Web. Another type of script language usually run under UNIX, CGIs are frequently written in C, Perl, or shell scripts, and are used for a variety of form-processing applications.
CISC	Complex Instruction Set Computer, a type of CPU that employs powerful, often elaborate, machine instructions often take several clock cycles to complete.
CMIP	Common Management Information Protocol, an OSI protocol for management of network equipment. Not widely implemented. See SNMP.
CMOT	CMIP over TCP/IP, a protocol consisting of CMIP running under TCP/IP. An alternative to SNMP.
CLEP	Competitive Local Exchange Provider, a Canadian term for parallel Telco exchange providers.
COM	Common Object Model, or a Domain on the Internet like EDU, GOV, ORG, and CA as in (WWW.FWMT.COM).
CPE	Customer Premises Equipment, that portion of the ADSL system residing within the customer's premises.
CRC	Cyclic Redundancy Check, an error checking technique: a way in which a frame or packet can be created in such a way that the receiver can determine whether an error is likely to have occurred in the transmission. An error will halt execution.
CSA	Canadian Standards Association, an independent agency for certification of products sold in Canada.
CSA	Carrier Serving Area, area served by a LEC, RBOC or Telco, often using Digital Loop Carrier (DLC) technology.
CSMA/CD	Carrier Sense Multiple Access with Collision Detection, the method by which nodes on an Ethernet/IEEE 802.3 LAN gain access to the network, i.e. one of several techniques that have been built into different LAN technologies to allow multiple nodes to share the same wires/electronics to send their data.
CSU/DSU	Channel Service Unit/Data Service Unit,
CUSeeMe	Said as it sounds, Video Conferencing Software, usually FREEWARE

DAS	Dual Attachment Station, a type of FDDI node that attaches to both rings of a counter-rotating ring to provide some fallback capability. The other type is SAS (Single Attachment Station). Typically, more vital FDDI nodes are DAS, e.g. routers, servers, links between hubs, and individual client stations are SAS.
DECNet	The Trade name of Digital Equipment's Corporation networking products. It is a kind of network built out of Digital Equipment Corporations own networking protocols (with some standard protocols also used).
DES	Digital Encryption Standard or Standards, cause there’s now more that one. A way of securing data from noisy people.
DHCP	Dynamic Host Configuration Protocol, a part of the TCP/IP suite of protocols for assigning IP numbers dynamically rather than fixed.
DOS	Disk Operating System, the software which provides an interface to hardware devices such as hard drives, memory, etc.
DoS	Denial of Service, a reference to any program, script, etc., which slows or halts some aspect of a system's function. Flooding and/or nuking are examples of DoS attacks.
DNS	Domain Name Server or Service an Internet phonebook you put in a name like “WWW.FWMT.COM” it translates it to 204.244.97.35 the IP address of our site. The system that translates human-readable addresses to IP addresses, and vice-versa.
DSLAM	Digital Subscriber Line Access Multiplexer, specifically a device which takes a number of ADSL subscriber lines and concentrates these to a single ATM line
DS0	Digital Signal 0, 64 KBPS digital representation of voice.
DS1	Digital Signal 1, twenty-four voice channels packed into a 193 bit frame and transmitted at 1.544 MBPS. The unframed version, or payload, is 192 bits at a rate of 1.536 MBPS
DS2	Digital Signal 2, four T1 frames packed into a higher level frame transmitted at 6.312 MBPS.
DSL	Digital Subscriber Line, modems on either end of a single twisted pair wire that delivers ISDN Basic Rate Access.
DXI	Data Exchange Interface. ATM Forum

E1	European basic multiplex rate which packs thirty voice channels into a 256 bit frame and transmitted at 2.048 MBPS.
EDI	Electronic Data Interchange,
EISA	Extended ISA, an other bus architecture that didn’t take, prior to PCI.
ELAN	Emulated LAN, essentially a fairly simple kind of VLAN defined in the ATM Forum's LANE specification. Unlike many VLAN schemes, the ELAN scheme is agreed upon by multiple vendors, i.e., the members of the ATM Forum.

FAQ	Frequently Asked Questions
FDDI	Fibre Data Distribution Interface, a LAN data-link protocol. Designed to run on multi-mode fibre. "Raw" rate of data transmission is 100 megabits/second. Developed by the American National Standards Institute.
FDDI-2	Same speed, same fibre, same basic protocol as FDDI. FDDI-2 adds a layer which allows you to allocate fixed bandwidth to applications of your choice, making it more like broadband. FDDI-2 is still rather new.
FDSE	Full Duplex Switched Ethernet, a variant of Switched Ethernet which does not use CSMA/CD, but uses slightly-modified network interface cards to send & receive packets simultaneously. Presumably based on 10BASE-T for most clients, and cannot be based on ThinWire or ThickWire Ethernet.
FEXT	Far End Cross Talk, the interference occurring between two signals at the end of the lines remote from the telephone switch.
FOIRL	Fibre Optic Inter-Repeater Link, a standard for running IEEE 802.3 over fibber, linking two devices (each either a host or a repeater) as a "Link Segment". It has been replaced by 10BASE-FL.
FTP	File Transfer Protocol, a protocol in the "TCP/IP" family for copying files from one computer to another.
FTTCab	Fibre To The Cabinet, network architecture where an optical fibre connects the telephone switch to a street-side cabinet where the signal is converted to feed the subscriber over a twisted copper pair.
FTTH	Fibre To The Home, a network where an optical fibre runs from telephone switch to the subscriber's premises or home.
FTTK or FTTC	*Fibre To the Kerb (Copper)*, a network where an optical fibre runs from telephone switch to a kerbside distribution point close to the subscriber where it is converted to a copper pair.
FDSEC	Full Duplex Switched Ethernet Consortium a group of vendors that are working out the details of FDSE. Cabletron is a member.

GIF	Graphic Interchange Format, a file format for saving graphics.
GOSIP	Government Open Systems Interconnect Profile, a subset of OSI standards specific to US Government procurements, designed to maximise interoperability in areas where plain OSI standards are ambiguous or allow options. Theoretically, required of all US Government networking procurements since mid-1990.
GSM	Global System for Mobil-communications, one of the two digital wireless standards for cellular.

HDLC	High-level Data Link Control, a low-level protocol used on synchronous WAN lines.
HDSL	High-bit-rate Digital Subscriber Line, remote access line above basic ISDN speed. Modems on either end of one or more twisted pair wires that deliver T1 or E1 speeds. At present T1 requires two lines and E1 requires three. See SDSL for one line HDSL.
HFC	Hybrid Fibre Coax, a system (usually CATV) where fibre is run to a distribution point close to the subscriber and then the signal is converted to run to the subscriber's premises over coaxial cable.
HiPPI	High Performance Parallel Interface,
HSSI	High Speed Serial Interface, a physical layer interface for serial communications between a DTE (e.g. a router) and a DCE (e.g. a DSU/CSU) that supports up to 52Mbps. Serves the same purpose as RS-232, but at a higher range of communication speeds. Used mostly for DS3 WAN links.
HTML	HyperText Mark-up Language A programming language.
HTTP	HyperText Transfer Protocol, the protocol that governs the transfer of WEB pages to WEB browsers.
HTTP-NG	HTTP-Next Generation

ICMP	Internet Control Message Protocol, a TCP/IP protocol used for sending error and control functions such as, Ping sents out ICMP echo requests. (Documented in RFC792)
ICP	Internet Control Packet, variant of IP protocols used in WAN's
IDC	Internet Database Connector
IEEE	Institute of Electrical & Electronic Engineers
IEEE 802	The set of IEEE standards for the definition of LAN protocols. A story goes that a long time ago, IEEE and ANSI decided that IEEE would get the slow protocols and ANSI would get the fast ones, thus IEEE defined the 802 protocols and ANSI defined FDDI. Presumably IEEE saw limited application for FDDI at the time. Also, the IEEE standards-making committees associated with these standards.
IEEE 802.1	The IEEE 802 standard for Network Management and Network Bridging of IEEE 802 networks. An algorithm, the original version of which was invented by DEC, used to prevent bridging loops by creating a spanning tree.
IEEE 802.11	Proposed IEEE 802 group for wireless Ethernet.
IEEE 802.12	Group within IEEE 802 working on 100VG-AnyLAN.
IEEE 802.2	An IEEE standard for the portion of LAN data-link protocols that is the same for all flavours of IEEE LAN protocols, e.g. 802.3 and 802.5. Sometimes not used.
IEEE 802.3	An IEEE standard for LANs--their "improved" version of Ethernet. See Ethernet.
IEEE 802.3u	The portion of IEEE 802.3 which defines the 100Mbps version, i.e. Fast Ethernet or 100BASE-T.
IEEE 802.4	An IEEE standard for LANs: Token Bus networks. Basically, standardises MAP, a protocol that operates a Token Bus protocol on broadband.
IEEE 802.5	An IEEE standard for Token-Ring-based LANs. There are two types: 4Mbps and 16Mbps. See also "Token Ring".
IEEE 802.6	An IEEE standard for Metropolitan Area Networks. Also known as DQDB.
IEEE 802.7	An IEEE 802 technical advisory group on Broadband.
IEEE 802.8	An IEEE 802 technical advisory group on FDDI & fibber optics.
IEEE 802.9	An IEEE 802 group on integrated data & voice networks.
IIS	Internet Information Server, Microsoft's now at ver. 4.
IJG	Independent JPEG Group
IMAP	Internet Mail Access Protocol, TCP/IP-based protocol similar to POP, but with additional function designed to handle storage of mail on the server rather than the client. There are two versions in common use: IMAP2 and IMAP4.
ISA	Integrated System Architecture, 16 bit slot for PC's
IP	Internet Protocol, The basic protocol of TCP/IP and the Internet.
IP	An address, A unique number fixed or assigned, that marks a location on the network, LAN/WAN or Internet
IRC	Internet Relay Chat, a popular service that allows users to talk with one another in individual rooms called channels.
IPX	Internetwork Pack Exchange, a Novell's protocol used by Netware IPX/SPX. Utilises parts of XNS. A router with "IPX routing" purports to interconnect LANs so that Novell Netware clients & servers can talk through the router.
ISAPI	Internet Services Application Programing Interface (Microsoft)
ISDN	Integrated Services Digital Network, a recent development in telephone/data communications that offers the subscriber digitised voice service and/or 64Kbps data service.
ISDL	Uses ISDN transmission technology to deliver data at 128kbps into an IDSL "modem bank" connected to a router.
ISP	Internet Service Provider, an organisation offering and providing Internet services to the public and having its own computer servers to provide the services offered.

JPEG	Joint Photographic Expert Group, an other graphics file format for video.
Kbps	Kilobits per second, A measure of transmission speed, a thousand bits per second.

LAN	Local Area Network a group of two or more computers connected together.
LANE	ATM Forum's method of using an ATM switch or switches to emulate an Ethernet or Token Ring LAN. The resulting "Emulated LAN" is called an ELAN, which can be thought of as a kind of fairly simple VLAN.
LCF-PMD	low-cost Fibre, PMD. FDDI in a less expensive than PMD. I don't believe it is common nor is it finished as a standard.
LEC	Local Exchange Carrier, one of the new U.S. telephone access and service providers that have grown up with the recent U.S. deregulation of telecommunications. LAN Switching, a term for bridging or cut-through switching, usually referring to a device with more than two ports.
LISP	List Processing Language

MAU	Media Adapter Unit, an IEEE 802.3 or Ethernet device which attaches a station to the cable. Popularly called a "transceiver". Can be attached by cable to the station or built into the station.
MAC	Media Access Control, a layer within the OSI Data Link Layer. every NIC has a MAC Address.
MAP	Translates a virtual address to a fixed address.
MPEG	Motion Picture Experts Group, the group that has defined the standards for compressed video transmission. Yet another video file format.
MIB	Management Information Base, the set of parameters an SNMP management station can query or set in an SNMP agent (e.g. router). Standard, minimal MIBs have been defined (MIB I, MIB II), and vendors often have custom entries. In theory, any SNMP manager can talk to any SNMP agent with a properly defined MIB.
MII	Media Independent Interface, an Interface much like the 10Mbps Ethernet "AUI" Interface only for 100Mbps Ethernet (100BASE-T, etc).
MIME	Multimedia Internet Mail Extensions, a protocol for sending enclosures in e-mail.
MPOA	Multi-protocol Over ATM, ATM Forum's method of using an ATM switch or switches to take the place of routing. The protocol/method is currently in development. As its name implies, it is intended to handle more than just TCP/IP, but TCP/IP support is what is being developed to begin with.
MUP	Multiple UNC Provider

NAP	Network Access Provider, another name for the provider of networked telephone and associated services, usually in the U.S.
NCSA	National Center for Supercomputing Applications
NDIS	Network Driver Interface Specification, a network driver unique to a NIC.
NEXT	Near End Cross Talk, the interference between pairs of lines at the telephone switch end. A diagnostic protocol.
NIC	Network Interface Card, a term used for the card you put in a PC to allow it to be attached to a network. The term and acronym is most often used with respect to IBM compatibles, and LANs such as Ethernet and Token Ring.
N-ISDN	Narrowband ISDN, same as ISDN
NFS	Network File System, an IP-based protocol originally developed by Sun Microsystems which provides file services.
NNTP	Network News Transfer Protocol,
NSP	Network Service Provider, the term for an organisation offering and providing value added network services on a telecommunications network.
NTE	Network Termination Equipment, the equipment at the ends of the line.
NUA	Network User Address, address for reaching a particular system via telenet.

OC3	Optical Carrier 3 ,: an optical fibre line carrying 155mbps; a U.S. designation generally recognised throughout the telecommunications community world-wide.
OCx	(e.g. OC1, OC3) variants of SONET.
OCX	From OLE “Object Linking and Embedding” controls, expanded and renamed ActiveX, the OLE controls are called OCX’s
ODAPI	Open Database Application Programming Interface [Borlund]
ODBC	Open DataBase Connectivity, a data connector for data exchange between different databases.
ONU	Optical Network Unit, a form of Access Node that converts optical signals transmitted via fiber to electrical signals that can be transmitted via coaxial cable or twisted pair copper wiring to individual subscribers.
OOB	Out Of Bound data, the method of "nuking" a windows system popularized in the past year. It involves sending random data to 139, the TCP/IP port for netbios. A stream of improperly formatted data sent to this port frequently causes crashes or freezes.
OSI	Open System Interconnect, a standard put forth by the ISO for communication between computer equipment and networks.

PCI	Peripheral Component Interconnect, variant of BUS connector for PC's
PCT	Personal Communications Technology,
PGP	Pretty Good Privacy, a public key cryptography system developed by Philip Zimmerman. It is free, and frequently used to encrypt e-mail.
PERL	Practical Extraction and Report Language, a programming language.
PMD	Physical Layer Medium Dependent, a FDDI part. When "PMD" is used by itself, it may refer to the usual kind of FDDI physical layer that uses multimode fiber. Note that FDDI terminology also uses it as a more generic term, referring to different FDDI PMD's such as TP-PMD and SMF-PMD.
POP	Post Office Protocol, a TCP/IP-based protocol designed to allow client-stations (e.g. micros) to read mail from a server. There are three versions under the name "POP": POP, POP2, and POP3. Latter versions are NOT compatible with earlier versions.
PON	Passive Optical Network, the usual acronym for a fibre based transmission network containing no active electronics.
POTS	Plain Old Telephone Service, the only name recognised around the world for basic analogue telephone service. POTS takes the lowest 4kHz of bandwidth on twisted pair wiring. Any service sharing a line with POTS must either use frequencies above POTS or convert POTS to digital and interleave with other data signals.
PPP	Point to Point Protocol, variant of serial connection usually for dail-up.
PTT	The generic European name usually used to refer to state owned telephone companies.

RADSL	Rate Adaptive ADSL, a version of ADSL where the modems test the line at start up and adapt their operating speed to the fastest the line can handle.
RAS	Remote Access Service, a dial-up service
RBOC	Regional Bell Operating Company. one of the seven U.S. Telephone companies that resulted from the break up of AT&T.
RC4	“Ron’s Code 4”
RFC	Request For Comments, the name is a real red herring when it comes to Internet RFC’s. Some really are "Requests For Comments" but all Internet protocol documents are stamped with an RFC number that they never shake, so the acronym RFC generally refers to documents that describe protocols in the TCP/IP family.
RISC	Reduced Instruction Set Computer, A CPU that employs a small number of simple instructions that are used in conjunction with other instructions to perform more powerful operations. Usually the type of CPU has a very large number of registers so it can perform many takes in a single clock cycle
RG#	A type of coaxial cable (E.g. RG62; sometimes there are qualifiers, e.g. RG 58 A/U) a shorthand designation for military cable. RG58 & RG62 designate two different types of cable used by the military. Some data-communications equipment was designed to work with a particular military standard, e.g. IBM 3270-type terminals use RG62. In other cases, people use an RG-numbered cable that is close to what they need: for example ThinWire Ethernet & IEEE 802.3 10BASE2 define the type of cable they need and people sometimes substitute flavours of RG58, which are "close". One can't recommend this practice because you can get yourself in trouble. I think "RG" originally stood for "Radio Guide", presumably reflecting the fact that the series of cables was designed to handle radio frequencies. The IEEE 802.3 10BASE2 specifications define two RG numbered cables (RG58 A/U and RG58 C/U) as meeting the cable requirements for thin Ethernet. However, cable vendors may list a range of cables under these same RG numbers, and some of the cables listed may not meet the 802.3 specs. You need to check the cable specifications closely, and beware of relying on the RG number alone when ordering network cables.
RJ#	Registered Jack, (numbers, e.g. RJ11, RJ45) numbers applied to types of connectors often used in UTP wiring. Borrowed from voice telecommunications industry.
RMON	Remote Monitoring,
RSA	Rivet-Shamir-Adleman,
RSVP	Resource Reservation Protocol" A method being developed by the IETF to assist in providing quality-of-service characteristics to communications over an IP network. The name refers to the fact that it allows the end-stations to reserve bandwidth on the network.

SATAN	Security Administrator's Tool for Administering Networks
SCSI	Small Computer Standard Interface, a port used to connect periferals to PC's
SDH	Synchronous Digital Hierarchy, Similar to SONET, but used outside North America. Some of the SDH and SONET standards are identical. Standardised by the CCITT.
SDLC	Serial Data Link Control, A low-level protocol used on synchronous WAN lines.
SDSL	Symmetric Digital Subscriber Line, HDSL plus POTS over a single telephone line. This name has not been adopted by a standards group, but is being discussed by ETSI. It is important to distinguish, however, as SDSL operates over POTS and would be suitable for symmetric services to premises of individual customers.
SGML	Standard Generalised Mark-up Language,
SID	Security ID
SLIP	Serial Line Internet Protocol
SMF-PMD	Single-Mode Fibre, PMD an FDDI mode. Runs further than PMD.
SMS	Systems Management Server
SNMP	Simple Network Management Protocol, Originally developed to manage IP based network equipment like routers and bridges, now extended to wiring hubs, workstations, toasters, jukeboxes, etc. SNMP for IPX and AppleTalk under development. Widely implemented. See CMIP.
SNA	Standard Network Architecture, IBM’s view of network management based around their AS400 Mainframe servers.
SMTP	Simple Mail Transfer Protocol, the protocol in the TCP/IP family used to transfer electronic mail between computers. It is not oriented towards a client/server system so other protocols (see "POP") are often used in that context. However, servers will use SMTP if they need to transfer a message to another server. See sendmail.
SONET	Synchronous Optical Network, a set of standard Fibre-optic-based serial standards planned for use with ATM in North America. Developed by Bellcore. Different types of SONET run at different speeds (OC1 runs at 51Mbps, OC3 runs at 155Mbps, OC12 runs at about 600Mbps, OC48 runs at over 2Gbps), and use different types of fibre (OC3 has several variants for use with different fibers & different distances; there are versions for both single mode and multimode fibre).
SQE Test	Signal Quality Error Test, an IEEE 802.3 function that tests the transceiver. The term "SQE" is often (wrongly) used interchangeably with "Heartbeat" which is a similar function of Ethernet Version 2. See Question on SQE/Heartbeat below.
SQL	Structured Query Language, a common script for querying databases.
SSI	Server Side Includes
SSL	Secure Sockets Layer, a protocol for secure sessions over the internet
STP	Shielded Twisted Pair, a type of network cable.
STS-1	SONET basic transmission rate of 51.84 MBPS.
SUID	Set User ID, a designation for UNIX programs that need the privleges of root when executing. Because they have superuser power, SUID programs are the most common targets of exploits.
SUN	Stanford University Network,

T1	A phone-company standard for running 24 digitised voice circuits through one 1.5megabit/second digital channel. Since phone companies run lots of T1, and will run T1 between customer sites, the standard is often used for data communications, either to provide 24 low-speed circuits, or to provide 1 high-speed circuit, or to be divided other ways. Same as DS1.
TAXI	Transparent Asynchronous Transmitter-Receiver Interface" Two ATM UNI specifications developed by Fore. The slower one ran at 100Mbps and borrowed the physical characteristics of FDDI and has been adopted by the ATM Forum as its 100Mbps UNI specification. The faster one ran at 140Mbps.
TCP/IP	Transmission Control Protocol/Internet Protocol, the standard most commonly used for networking on the internet, literally, two protocols developed for the Defence Data Network to allow their ARPANET to attach to other networks relatively transparently. The name also designates the entire family of protocols built out of IP and TCP. The Internet is based upon TCP/IP.
Telco	The generic name for telephone companies throughout the world which encompasses RBOCs, LECs and PTTs.
TP	Twisted Pair, a type of cable
TPON	Telephony over Passive Optical Network, a telephony using a PON as all or part of the transmission system between telephone switch and subscriber.
TP-PMD	Twisted Pair Physical Layer Medium, FDDI. ANSI specification for FDDI-like service over UTP. Being standardised by ANSI X3T9.5. Was X3T9/93-130 X3T9.5/93-022 TP-PMD/306 Rev 2.0, now there is a Rev 2.1. Uses MLT-3 encoding instead of CDDI's NRZI encoding.

UDP	Universal Data Packet, TCP/IP protocol.
UDSL	Unidirectional HDSL, as proposed by one company in Europe without much sign of interest from anyone else.
UDP	User Datagram Protocol, a connectionless TCP service
UNC	Uniform Naming Convention, network naming convention for servers on a network
UID	User Identifier, a 16-bit integer that is mapped to a username on UNIX systems. UNIX identifies a user by this number, not the username itself.
UNI	User to, an ATM Forum. See ATM.
UNIX	Uniplexed Information and Computing System, a multiuser, multitasking operating system primarily used on workstations and servers. Most internet servers run some variant of UNIX.
UPS	Uninterruptible Power Supply, power backup system for PC's or phone systems.
URL	Uniform Resource Locator, server
USB	Universal Serial Bus, yet another port for connecting peripheral to a PC.
UTP	Unshielded Twisted-Pair” See "Twisted-Pair" and "Shielded Twisted-Pair
UUCP	UNIX to UNIX CoPy, an old service used to directly transfer files from one computer to another. It was mostly utilized for mail transport.

VADSL	Very high speed ADSL” basically the same as VDSL (or a subset of VDSL, if VDSL includes symmetric mode transmission)
VBS	Visual Basic Script, a programming language
VCRS	Voluntary Content Rating System
VDM	Virtual DOS Machine, a way to run legacy DOS apps under newer operating systems
VDSL	Very high data rate Digital Subscriber Line, a modem for twisted-pair access operating at data rates from 12.9 to 52.8 MBPS with corresponding maximum reach ranging from 4500 feet to 1000 feet of 24 gauge twisted pair.
VLAN	Virtual LAN, a portion of one or more LAN switches which delivers packets as if it were a physical LAN; actually like a switched LAN. It is a feature planned or included in numerous LAN switches. VLAN is a well-known industry buzzword as of 1995 and 1996 and is not used consistently throughout the industry. The most primitive VLAN facility that a switch can have allows the switch to be partitioned into two or more groups of ports (VLANs) within which communication is possible, but between which communication is blocked. More complex is a feature which allows each VLAN to reside on two or more switches (e.g. some of VLAN A's ports are on switch 1 and some of its ports are on switch 2; and the same for VLAN B) even though the two switches are connected through a single physical interface. The most complex is provision for VLANs that overlap, i.e. port 1 of a switch is on VLAN A and VLAN B, while port 2 is on VLAN A but not VLAN B, etc. The term "Virtual Network" is also used.
VMRL	Virtual Reality Modelling Language, variant of programming language.
VMS	Virtual Memory System, an operating system designed for Digital's 32-bit VAX (Virtual Address eXtension) computers. Like UNIX, it is frequently used in server and workstation applications.
VPN	Virtual Private Network, a WAN connection over the cloud, made private through packet encryptions and routing control.

W3C	World Wide Web Consortium, Moulder and Skully’s next big case.
WAIS	Wide Area Information Server, Microsoft’s version of EMWAC
WAN	Wide Area Network” Private network facilities, usually offered by public telephone companies but increasingly available from alternative access providers (sometimes called Competitive Access Providers, or CAPs), that link business network nodes. A term for state/country/world-wide networks developed to parallel the term LAN.
WAP	Wireless Application Protocol, is an open, global specification that empowers mobile users with wireless devices to easily access and interact with information and services instantly.
WINS	Windows Internetwork Name Service, Microsoft's variant of DNS for a Netbios network.
WWW	World-Wide Web, or better known now as “World-Wide Wait” on the Internet, the name of the host for that web page!

XYZ

X.25	Protocol used for inter-computer communications over WANs.
X.400, X.500	OSI protocols for mail and directory services.