ACK is TCP flag that acknowledges receipt of a TCP segment.
- Advanced Research Projects Agency Network
ARPANET was early network established in 1972 between a few research
nstitutes and universities in the USA that evolved into the Internet
Java program that can be embedded in an HTML page. They have security
restrictions and cannot access file system, launch processes or make system
calls on the local computer.
- application layer
Level of network reference model that interfaces below with transport
layer and above with user.
- application programming interface
API is set of procedures, methods, types and so on defining a set of
application services and how to invoke and handle them from a programming
- Asymmetric Digital Subscriber Line
ADSL is version of Digital Subscriber Line that uses most of the channel to
transmit to the user.
- Asynchronous Transfer Mode
ATM is a connection oriented, high speed switching technology that organises
digital data into 53 byte cells to transmit them over physical media. Cells
can be rapidly processed asynchronously by hardware and multiplexed in
Authentication is process of determining that an entity is who or what it
claims to be.
Authorisation is process of determining what services and resources
an entity can use.
A bastion is a firewall that is the gateway between a LAN and the Internet.
standard for small-form factor, low-cost, short range radio links
between mobile PCs, mobile phones and other portable devices based on
spread spectrum radio communications.
BOOTP is the Bootstrap protocol used by by discless hosts to discover their
IP address, the location of the boot server and to start system download over
tftp prior to booting.
Device connecting two networks at the data link layer level that filters
and forwards packets across divide both ways but doesn't alter format or
contents of packets passed.
Broadcast is an IP packet sent to all interfaces connected to the same
- broadcast network
Type of network in which all connected hosts share a single communication
channel. It is the opposite of a point to point network.
Intermediaries in network applications that add value to the
provision of services. Brokers may find servers for clients or refine service
requests for clients. Unlike proxies, brokers don't mask their role as
intermediaries between clients and servers.
Looking for resources of interest in a reactive process of exploration where
the seeker has no precise search objective. It can be contrasted with
Shared communications link interconnecting multiple local devices that
pairs of communicating parties must take turns using.
- byte code
Compiled form of a program in a language such as Java which can be executed
on an emulator for that code such as a Java Virtual Machine. Java byte code
is stored in ".class" files.
Fast access storage units placed on communication links to improve effective
bandwidth from remote sites. They exploit locality of reference by storing
recent copies of previously fetched data and let the cache try to service data
- cache consistency protocol
Protocol for ensuring that the data stored in a cache is a valid copy of the
data it purports to be a copy of.
CERT stands for Computer Emergency Response Team, an information coordination
centre and Internet security emergency prevention centre formed at Carnegie
Chain is a list of rules defining what packets can come in and go out
through a network interface.
Recursive forwarding of a X.500 directory service query to directory service
agents able to process the various parts of it and the subsequent marshalling
of these replies into its own reply.
Checksum is a number produced by arithmetic on each byte in a file or packet
so that if the file or packet is changed or corrupted, the same checksum
will no longer be produced.
Type of network infrastructure that establishes point to point connections to
communicate along in the style of telephone calls. Opposite of packet-switched.
- Common Gateway Interface
standard used by web servers to interface web clients to programs. It is
primarily used to process forms and return results and as a gateway to third
tier applications such as databases
Hardware or software acting as service consumer usually using a client server
model of computing
- client pull
Term for push technology application on the web in which the client regularly
or irregularly pulls data from a web server.
- client server model
Model of distributed computing based upon a passive service provider or
server waiting to receive requests from one or more active service
consumers or clients to which it responds by providing service.
- communication domain
Socket addressing scheme which is either Internet domain or Unix domain.
Internet domain addressing uses Internet domain names or IP
addresses and port numbers and has the scope of the Internet. Unix domain
addressing uses local file names and has the scope of the local host.
- Common Object Request Broker Architecture
CORBA is powerful programming language and operating system neutral API for
realising distributed systems of objects that is being developed by
Computer based realisation of synchronous or asynchronous multiparty
- connection-oriented communication
Communication is connection-oriented if identity of each endpoint is
established at start of communication, is maintained at each end for
presentation at any time, and is not transmitted with each packet of data
- context switch
Switching of processor from executing one thread or process to executing
Small item of persistent data stored by a web browser on local filespace
of client's host in accordance with <a href="cookie_spec.html">Netscape</a> or
Computer Oracle and Password Systems or COPS is a suite of programs
that check for security vulnerabilities on UNIX operating systems.
Posting of news article on news service to several different newsgroups.
- Cascading Style Sheets
CSS is stylesheet language for HTML and XML documents that controls their
layout and formatting.
Process providing network or operating system services on demand.
Packet of data.
- datagram socket
Socket suitable for datagram communication in a connectionless, unreliable
manner where each communication packet must be addressed and may be
duplicated, reordered or lost in transit. It is realised by use of the UDP
- data link layer
Data link layer is the second layer in the OSI reference model that handles
point to point data delivery between two adjacent network devices.
- denial-of-service attack
Denial-Of-Service attack is an attack based on flooding a network or host
with packets so as to disrupt or seriously impair network performance or
that host's performance.
Deny-all is a policy for packet filters that drops all packets.
- Dynamic Host Configuration Protocol
DHCP is a protocol used to assign IP addresses to hosts without them. It also
supplies server and router information.
- Dynamic HyperText Markup Language
create animation and interaction by manipulating styles and HTML documents.
- Digital Subscriber Line
DSL is standard for high bandwidth communications on existing phone lines
that is continuously available. It also accommodates voice on same line.
Hierarchically structured set of associations between a name, an object and
attributes of the object.
- directory service
Online, directory based, lookup service that supports indexed access via
hierarchies to resources; they supply details on people, network services,
- Document Object Model
DOM is a specification allowing all elements of a Web page, including styles,
to be manipulated and acted on by programs and scripting languages. Currently
the document object model supported by Netscape and IE are slightly different,
but the W3C is defining a standard DOM that will be used by both in the future.
- domain name
Compound textual name for computers attached to the Internet such as
adam.astro.yale.edu. It is interpreted using the domain
- Domain Name System
DNS is a hierarchically structured, distributed information system on the
Internet whose main function is to allow domain names for Internet hosts to
be resolved into the numerically based IP addresses for these hosts used by
the Internet's packet routing system.
Software that can control and run other software through its interface. Typical
drivers simplify the task of running software through complex interactive
- Document Type Definition
DTD is a formal description of the allowed elements, attributes and entities
in a particular type of document. In SGML in defines the grammar of a
particular markup language.
- Data Transfer Process
DTP handles communication of data between FTP peers.
- Demilitarized Zone
DMZ is a less secure perimeter network containing hosts for public services
that is separated from from a local, private network.
- Dublin Core
15 element metadata standard that aims to facilitate discovery of electronic
Electronic mail is computer based messaging system modelled on postal mail that
sends, receives and stores messages solely within electronic media.
- e-mail filter
Software that automatically processes e-mail messages in a user's mailbox on
the basis of a set of filtering rules. These rules cause messages to be
deleted, saved in special folders, forwarded, or automatically replied to.
Filter actions are usually triggered by pattern matching on e-mail message
- e-mail gateway
Software that handles the exchange of e-mail messages between different e-mail
systems such as Internet e-mail, X.400 or MS-Mail. E-mail gateways translate
between message formats, addressing schemes and use of transfer protocols.
- e-mail list
Moderatable facility whereby all subscribers receive by e-mail a copy of each
article sent to address of e-mail list.
Named object in an XML document. Often a character or character sequence
that cannot be easily represented on all platforms, so is referred to by name
using an entity reference.
- entity reference
Reference to a named object (normally a sequence of characters) in an XML
document. The entity reference may be replaced by the referred to object when
the document is processed.
- ethernet frame
Ethernet frame is an encapsulation of an IP datagram at the data link layer
in accordance with the Ethernet standard.
- event handler
Piece of program that executes in reaction to an event. When a user clicks on a
causing the display to change in some appropriate way.
Less secure network external to an organisation's secure organisational
network that is open to access both from wide area networks and the
organisation's internal network.
- Fibre Distributed Data Interface
FDDI is standard for data transmission on fibre optic lines up to 200 kms
range and with a 100 Mbps capacity.
- File Transfer Protocol
FTP is an application level protocol defined in
covering the passing of files across the Internet.
TCP based Internet protocol specified in
for requesting information about which users are logged into an Internet
host or for requesting more detailed information about a particular user.
Network gateway that filters network traffic to limit access either way only
to allowed services. It is often used to protect the security of a LAN from
hostile access from a WAN connection such as the Internet.
Starkly critical news article of another's news postings. Breach of
netiquette is a common reason for this.
Flooding is the practice of sending copies of data such as an IP packet
along all available network paths.
- flow control
Flow quenching mechanism used in reliable communications protocols to
regulate the flow of information that lets a process receiving the flow
temporarily stop the generating process until the receiving process
is able to handle more information.
Act of process creation in Unix by duplication of an existing process.
Forwarding is the practice of sending packets from one network to another
in accordance with their network addresses in order to deliver them to their
Fragment is a portion of something such as a TCP segment that lies within
something else such as an IP packet.
Full OS computer sitting on 2 networks that connects them at the application
layer level. It can translate between different network protocols on the two
networks and can proxy & broker at the application level.
- General Packet Radio Services
is a new nonvoice value added service that allows information to be sent
and received across a mobile telephone network. It supplements today's
Circuit Switched Data and Short Message Service.
- Global System for Mobile Communications
is the main wireless digital technology for cellular phones in the world.
- Graphical User Interface
GUI supports windows, menus, icons and pointers. Examples include X Window,
MacIntosh user interface and Microsoft Windows.
- GUI terminal
End user computing device enabling access to personal computing applications
that processes graphics operations locally but requires all other application
processing to be done on remote servers.
is standard for sending audio and video data across IP networks.
- helper application
Separate program invoked by a web browser to provide functionality to render
web resources such as video files that the browser cannot handle itself.
- hop count
Small counter added to broadcast packets to stop datagrams looping round in
networks. Whenever a gateway open to broadcast traffic encounters a broadcast
packet, it decrements the hop count by 1 before rebroadcasting the
packet on the other side of the gateway. Broadcast packets with a 0 hop
count are never passed on.
Networked computer offering services to other computers on a network.
Hub is hardware that repeats signals in order to connect multiple network
segments together in a physical way.
Hyperlinks link documents together. A user can navigate from one document to
another by clicking on the hyperlinks, which are commonly indicated as
Multimedia resources linked together in the manner of hypertext.
Text that contains links to other documents, such that if words or phrases are
selected by the reader another document is retrieved and displayed.
- HyperText Markup Language
HTML is a language used to create hypertext documents for use on the World
- HyperText Transfer Protocol
HTTP is stateless, network application protocol to handle information transfer
in the distributed, collaborative, hypermedia information system called
the World Wide Web.
TCP based Internet protocol specified in
for asking a remote host the system name of the user who is behind a TCP
connection established between that remote host and the local host.
- Interactive Mail Access Protocol
IMAP is an ascii network application layer protocol suitable for interactive
and programmed use to access e-mail dynamically from a mailbox server. It is
Its latest version is IMAP version 4. It is more sophisticated than
POP, supports concurrent access and is more suitable for use where only
selective retrieval of e-mail messages is needed.
- information retrieval system
IR systems store text and are geared for fast indexing of stored text by word
or string matching. They are used in libraries, in online bibliographies and
catalogues and in office automation systems.
- Internet Control Message Protocol
ICMP is protocol defined in
that is an integral part of IP and is used for reporting errors in the
processing of IP datagrams.
World's largest world wide network of networks or internetwork based on the
use of the TCP/IP protocols.
- Internet Architecture Board
IAB is small group that oversees IETF and provides leadership on standards
and evolution of Internet. It is chartered by
- Internet Corporation for Assigned Names and Numbers
ICANN is non-profit corporation responsible for IP addresses, domain names,
protocol parameters and supervises control of root server system of DNS.
- Internet Engineering Task Force
IETF is community of network designers, operators, vendors & researchers
concerned with evolution and operation of Internet. It works in groups
with a charter.
- Internet Protocol
IP is network layer protocol defined in
for passing packets of data across networks that is used on the Internet.
- Internet Protocol address
IP address is 32 bit integer address of Internet host that is often
represented in dot form like this 18.104.22.168 where each dot delimited
sequence of up to 3 digits represents one byte (0 to 255) of 4 byte address.
- Internet Relay Chat
IRC is network application level textual conferencing
protocol defined by
- Internet Assigned Numbers Authority
IANA is the precursor body to ICANN that was subsumed by it in 1998.
It manages the DNS Root Zone, coordinates the global IP and AS number space
with Regional Internet registries and acts as the central repository for
protocol name and number registries, used in many Internet protocols.
- Internet Research Task Force
IRTF promotes research important to evolution of Internet and is composed
of focused, long-term, small research groups.
- Internet Societal Task Force
ISTF is body that identifies ways in which Internet can be a positive force
in social and economic dimensions and aims to describes steps to assure that
Internet is for everyone. It does its work through discussion lists,
white papers, local educational initiatives and workshops.
- Internet Society
ISOC has mission to provide leadership in developing the Internet, charters
various Internet bodies - IESG, IAB and IETF and licenses their setting of
Internet infrastructure standards.
Connection of different networks such as Internet.
- Integrated Services Digital Network
ISDN is a set of standards for digital transmission over ordinary telephone
copper wire at a variety of higher speeds than over modem connections. It
requires adapters at both ends of the transmission.
Organised provision of Internet services such as the web, e-mail, news etc.
on an organisation's secure internal network.
- interprocess communication
IPC is communication between processes that are usually but not necessarily on
- Java DataBase Connectivity
JDBC is Java API for remotely accessing relational databases using SQL
- Java Naming and Directory Interface
JNDI is a Java API for writing applications that access naming and directory
- Java Server Pages
JSP is scripting extension of servlet technology that enables dynamic content
authoring at HTML or XML level.
Commercially unsuccessful but historically important network computer
developed by Sun Microsystems in 1997.
- Java Virtual Machine
JVM is abstract machine for executing compiled version of Java.
It can be realised in a variety of ways including by software emulation.
- Lightweight Directory Access Protocol
LDAP is simplified version of the X.500 Directory Access Protocol defined in
- Local Area Network
LAN is privately owned network housed within single building or campus of few
kms in size that is often a broadcast network in a bus, ring or star
File or store recording the e-mail messages sent to an e-mail recipient.
Large, powerful and expensive computer usually with a highly reliable,
proprietary operating system providing traditional computing services
such as batch processing in a centralised manner
Characters or other symbols inserted in a text to indicate how it should be
displayed or to describe the document's logical structure. Markup indicators
are sometimes called "tags."
Data describing attributes of information resources.
Language used to define or talk about other languages.
- Metropolitan Area Network
MAN is private or public city sized LAN that supports data, voice and even
video. It often lacks switching elements & may have a dual bus structure.
Software components in a distributed system that form a middle tier of
processing between client applications interfacing with users and backend
components such as databases or application servers.
Server replicating service provided by a server elsewhere. Mirrors can
relieve congestion at a site by splitting a server's load or offer a faster
fetch of information from a local replica of the service than from the remote
- Multipurpose Internet Mail Extension
MIME is two part Internet classification scheme for media types of online
resources such as audio, video and text files
Sending messages from one host to multiple hosts.
Process based multiprogramming.
Form of program execution in which several programs are stored in main
memory at same time and each program is executed as separate thread or process
with execution chances on the processor being shared among them.
Thread based multiprogramming.
- name resolution
Process of using a naming service to look up what a name refers to.
Mechanism enabling XML authors to use element names defined by others by
using prefixes associated with a unique URI.
- naming service
Network service supporting a naming scheme in which network applications are
able to look up names and update the bindings of names.
Term for push technology application on the Internet.
- network address class
Network address class is one of 5 ranges of IPv4 network addresses labelled
A, B, C, D and E that depends on whether the 4 most significant bits are less
than 128, between 128 and up to 192, between 192 and up to 224, between 224 and up to 240 or 240 and above.
- Network Computer
NC is end user computing vehicle supporting GUI and application processing but
no persistent local storage of data.
- network reference model
Layered model for understanding how a computing network functions in
terms of the protocols it uses. OSI networks have a 7 layer reference model
and TCP/IP networks have a 5 layer reference model.
- net PC
PC without a floppy drive or with the floppy drive blocked.
- network architecture
Model of a network as a set of network layers with their associated protocols.
- Network News Transfer Protocol
NNTP is ascii protocol for interactive and programmed use to support
distribution, inquiry, retrieval & posting of news articles. It is
- network layer
Layer of TCP/IP network architecture that provides connections and routing of
packets in network including handling and decoding of packet addresses and
maintaining routing data for proper response to load.
- network news
Forum based electronic messaging medium for asynchronous discussion
whose largest realisation on the Internet is called USENET News and
is mostly realised by NNTP.
Newcomer to an online discussion medium such as Internet Relay Chat or USENET
News. Usually used as derogatory term for newcomers who display
characteristic ignorance of conventional good practice in their
Major source of news articles for a news server.
Named forum for online discussion in online news service.
- New Technology
NT is operating system designed and developed in the early
1990s originally as a file and print server for PCs and for single user
workstations by Microsoft. It has evolved into a multi-user, general purpose,
modern operating system for a wide range of computing platforms.
Its current incarnation is called Windows2000, XP or NT5.
- Network Virtual Terminal
NVT is virtual device providing standard, network-wide, intermediate
representations of canonical terminals. It is a key abstraction used by
- object oriented database
Database management system that supports the modelling, storage and retrieval
of data as objects in the sense of object oriented programming languages. It
is suitable for handling storing complex, hierarchies of objects. See the
Object-Oriented Database System Manifesto
- Open DataBase Connectivity
ODBC is standard API for remotely accessing relational databases based
around the SQL call-level interface
- Online Public Access Catalogue
OPAC is online catalogue open to public usually of a library's books. Typical
systems are often based on the Z39.50 protocol.
Type of communication on a communications medium that is sent immediately
and directly and isn't held up by any non-out-of-band messages already in the
Small amount of data with a header detailing how to handle its contents
that is used by network protocols as its standard unit of communication.
Type of network infrastructure that mixes together packets for different
destinations and routes them according to their address in the style of
postal mail. Opposite of circuit-switched.
Fixed size block of memory used for handling data in chunks.
- Personal Computer
PC is computer supporting GUI, local application processing, persistent
local storage of data and a single user operating system. Examples include
Windows PCs and MacIntoshes.
- physical layer
Layer of TCP/IP network architecture that handles (electro)mechanical details
of bit transmission.
Network utility providing a low interference way to see if a remote
host is alive. It can also be used to time how long communication with a
remote host takes.
Code module that can be installed in a web browser to extend its
functionality in an integrated way. Popular web browsers support plug-ins for
playing sound files, movies or streaming media, for presenting documents in
various formats, and for supporting multimedia productions, virtual
environments or interactive animations.
- point to point network
Type of network in which hosts are connected by multiple connections and
packets usually have to be routed via intermediate hosts to reach their
Address used for an Internet transport protocol communication end point. It
has a value between 1 and 65535 and a type of either TCP or UDP. Port numbers
between 1 and 1023 are usually reserved for exclusive use by privileged users
and typically for well known services.
- Point to Point Protocol
PPP is a data link layer protocol often used to connect PCs via modems to
- Post Office Protocol
POP is network application protocol defined in
to access mail dynamically from a mailbox server
Interruption of execution of process or thread during time-sharing execution
before its time-slice has expired in order to context switch to another
process or thread which has been given execution priority over it.
- prioritised scheduling
Scheme for scheduling the execution of runnable processes or threads that
favours those with a higher priority.
Executing or executable task on a computer with its attached resources.
Rules and conventions used in interprocess communication governing the
formats of data exchanged, the structuring of the dialogue and the handling
of exceptional circumstances.
- protocol stack
List of network protocols, one per network layer.
Proxy is a surrogate for a service provider that emulates the provision of
its services. Proxies are used as intermediaries in network applications
between clients and servers in order to speed up, replicate, monitor or
safeguard service provision.
- peer to peer model
Model of distributed computing based upon two or more distributed processes
that both consume and provide services to each other and are at times active
and at other times passive.
- publish and subscribe model
Model of distributed computing based upon a service provider or publisher
generating a stream of data along a channel and a service consumer or
subscriber receiving the stream so long as it subscribes to service.
- push technology
Technology based on service providers providing enduring (information)
services to consumers at the initiative of the provider. It is based on the
publish and subscribe model not the client server model.
- quoted printable
Character encoding scheme in which encoded characters are represented by
three characters - "=" followed by two hexadecimal digits representing the
byte value. It is intended for encodings of text where the vast majority of
the text is unencoded and only a small proportion of it such as Ascii values
over 127 is encoded.
- Remote Method Invocation
RMI is powerful Java API for invoking methods on remote Java objects that
provides a general means for realising distributed systems of objects.
RPC is procedure P that a caller process C gets a server process S to execute
as if C had executed P in C's own address space.
specifies an "Open Network Computing" version of RPC.
Device connecting two physical layer components on networks that aims to
regenerates attenuated and distorted signals to permit signal to be sent
- Request For Comment
RFC is authoritative series of online documents published on the Internet
giving details of standards, proposed standards or other
information relevant to use of Internet. RFC authoring is controlled by
the RFC editor who is appointed by the IESG and is primarily for IETF
- Resource Description Framework
RDF is XML
standard for metadata
developed in 1999.
- resource discovery
Term used for issues concerned with finding information resources
on electronic information media such as the WWW, USENET news archives
and FTP sites.
Device connecting two networks of same type at the network layer level that
processes packet headers, picks route for packets and is an addressable node
Network utility that produces and consumes status information on local hosts.
It is exercised by the rwho command which shows who is logged in on local
machines and the ruptime command which shows how long local machines have
Similar to a DTD, a schema describes the allowed elements in a document.
Schemas are written in XML, and have additional functionality beyond DTDs,
through the use of complex type definitions.
- scripting language
Interpreted programming language which is designed for rapid programming
of lightweight tasks. For convenience it is usually weakly typed.
Goal driven rather than exploratory form of resource discovery where the
seeker has a specific informational objective. It can be contrasted with
CSS way of identifying which style declarations are associated with which
elements of a document. Simple selectors apply to a named HTML element, such
as <h3> or <p>.
- Serial Line Internet Protocol
SLIP is a link layer encapsulation protocol for sending IP packets along
serial lines such as modems
Hardware or software providing computing service usually as
part of client server model of computing
- server push
Term for push technology application on the web in which the server regularly
or irregularly sends data to a waiting web client which uses it to update its
Java API extending functionality of servers using request reply protocols.
Servlets are most often used by web servers to interface web clients to
programs in a similar manner to CGI.
Plug-in made by Macromedia for viewing animations and multimedia.
- Short Message Service
text messaging service
used to send and receive text messages from mobile telephones.
- Simple Mail Transfer Protocol
SMTP is Ascii protocol defined in
that is suitable for interactive and programmed use for sending
mail messages to Internet mail message transfer agents.
- Simple Network Management Protocol
SNMP is protocol for managing network elements described in
Communication endpoint using the TCP or UDP transport protocols usually for
establishing point to point communications between processes on the Internet.
Unsolicited and unwanted e-mail or the action of flooding someone's mailbox.
- stream socket
Socket suitable for byte stream communication in a connection-oriented
manner, that is reliable, order preserving and flow controlled. It supports
out of band communication and is realised by use of the TCP transport
Instructions concerning a document's appearance. CSS and XSL are both
stylesheet languages for the World Wide Web.
- Standard General Markup Language
SGML is a standard for creating markup languages. HTML is a specific markup
language based on SGML.
Symbols used to define HTML and XML elements. An element, such as a heading,
is normally delimited by a start tag, such as <H1> and an end tag, such as
Remote login facility of Internet described in
- thin client
End user computing vehicle enabling access to personal computing applications
but having less than the full range of PC capabilities to keep its cost and
size down. Examples include GUI terminals such as Winterms or X terminals and
Network Computers such as Java Stations.
Identifiable computation unit with state executing a task
Multiprogramming where threads or processes are run for a time-slice and then
context switched to allow other runnable threads or processes a chance to
Quota of time allocated to a process or thread to be executed before context
switching to another runnable process or thread of equal priority during
- time to live
TTL is quota of time left to a cached resource during which it is deemed to
be a fresh copy of its original.
Network utility that prints route that packets take to a remote network host.
- transport layer
Level of network reference model concerned with handling low level access to
network and transfer of messages among nodes including partitioning messages,
keeping packet order, flow control & address generation
- Transmission Control Protocol
TCP is a reliable, connection-oriented transport protocol defined in
for IP networks that supports flow control and out-of-band communication.
- TCP/IP Network Reference Model
Network reference model for TCP/IP networks that views it as having 5 layers
- application, transport, network, data link and physical.
- Uniform Resource Characteristics
Metadata specification for a URI.
- Uniform Resource Identifier
URI is an identifier for an online or offline abstract/physical resource
composed of a compact sequence of characters (alphanumerics & a few symbols)
which is either a URL or URN. It is specified in
- Uniform Resource Locator
URL represents location and access method of Internet resource with the
general form <scheme>:<scheme-specific-part>. It is defined by
- Uniform Resource Name
URN is a designation in a extensible, scalable name space for web resources.
It offers a globally unique, location independent name that continues to have
meaning even after the lifetime of resource. URNs are intended to be
resoluble to resources, URLs or URCs by a network accessible service that has
yet to be established.
Universal character set standard that uses 16 bits to encode characters,
allowing far more characters to be encoded than ASCII (which uses 8 bits).
Widely used modern network operating system suitable for computers from
laptops up to mainframes and supercomputers.
- USENET News
Internet based set of discussion forums organised in hierarchical structure
of over 10,000 newsgroups and largely implemented using the NNTP protocol.
- User Datagram Protocol
UDP is a simple transport level protocol defined in
for nonreliably passing datagrams across the Internet.
- Voice over IP
Set of facilities for arranging the delivery of voice data over IP networks.
This usually means sending voice as discrete packets of digital data over the
Internet rather than as analogue electrical signals in the circuit-switched
manner of traditional telecommunications networks. It saves on phone bills
but risks audio quality if transient network congestion delays voice data
- Virtual Reality Modeling Language
VRML is a high level modelling language for virtual environments defined by the
Warez is pirated material such as copyrighted works traded in violation
of copyright law.
- Warwick Framework
Container architecture for handling metadata.
Short for World Wide Web.
Term for push technology application on the web.
Computer based collaborative tool accessible from multiple networked
computers consisting of a drawing space upon which users may mutually
communicate graphics and interactive drawings.
- white pages
Directory service of people's names, addresses and locations.
- Wireless Application Protocol
is a protocol for a mobile phone to talk to a server installed in a mobile
phone network. A WAP gateway enables a mobile phone to communicate with
standard network computing services.
- Wide Area Network
WAN is large scale network covering a country or large geographic region. It
usually consists of transmission lines and switches, has irregular topology
and is often packet switched.
Powerful end user computing vehicle running sophisticated operating
system such as UNIX or NT.
- World Wide Web
WWW is distributed hypermedia information system running on the
Internet that refers to resources using Uniform Resource Locators or URLs,
moves resources using the HyperText Transfer Protocol or HTTP and uses a
scripting language called HyperText Markup Language or HTML to support
hyperlinking of these resources
Network application protocol defined by
to provide a network transparent graphical user interface primarily for
the UNIX operating system.
Powerful directory service protocol defined by ISO 9594
and explained in
- eXtensible HyperText Markup Language
XHTML is reformulation of HTML 4.0 in XML allowing improved interoperability.
- eXtensible Markup Language
is simplified form of SGML developed by W3 consortium that provides
standard syntax for grammatically validatable document markup and data
exchange. It is intended to replace HTML as markup language for
World Wide Web.
- eXtensible Stylesheet Language
XSL is language for creating a stylesheet specifying how an XML
document should be presented to the user. It also contains rich mechanisms
for translating XML documents from one form to another and to HTML.
- yellow pages
Network lookup service for system data based on distributed database of
maps whose records are looked up by their keys.
Unix process, which has terminated, and given up all its resources, but has
not yet performed its final act of notifying its parent of its demise.
Zombies continue to occupy slots in the Unix process table.
- zone transfer
AXFR is a DNS query request explained in
asking a DNS server for all resource records from a zone. The primary purpose
of a zone transfer is to allow a secondary DNS server for a domain zone
to refresh its knowledge of the domain from the primary DNS server. Many
authoritative DNS servers refuse to honour zone transfer requests from
anything other than secondary DNS servers.
Standard protocol for accessing information retrieval systems. It is used with
online public access catalogues like library catalogues.
Advanced Research Projects Agency Network
Application Programming Interface
Asynchronous Digital Subscriber Line
Asynchronous Transfer Mode
Common Gateway Interface
Carriage return '\r' followed by linefeed '\n'
Common Object Request Broker Architecture
Cascading Style Sheets
Defense Advanced Research Projects Agency
Dynamic Host Configuration Protocol
Dynamic HyperText Markup Language
Domain Name System
Document Object Model
Digital Subscriber Line
Document Type Definition
Data Transfer Process
Electronic Data Interchange
Fibre Distributed Data Interface
File Transfer Protocol
General Packet Radio Services
Global System for Mobile communications
Graphical User Interface
HyperText Markup Language
HyperText Transfer Protocol
Internet Architecture Board
Internet Assigned Numbers Authority
Internet Corporation for Assigned Names and Numbers
Internet Control Message Protocol
Internet Engineering Steering Group
Internet Engineering Task Force
Internet Mail Access Protocol
Inter Orb Reference
Internet Relay Chat
Internet Research Task Force
Integrated Services Digital Network
Internet Service Provider
Internet Societal Task Force
Joint Academic NETwork
Java DataBase Connectivity
Java Distributed Object Model
Java Naming and Directory Interface
Java Server Pages
Java Virtual Machine
Local Area Network
Lightweight Directory Access Protocol
Metropolitan Area Network
Message Digest 5
Multipurpose Internet Mail Extensions
Maximum Transmission Unit
Network Address Translation
Network File System
Network Information System
Network News Transfer Protocol
New Technology operating system
Network Virtual Terminal
Open DataBase Connectivity
Object Management Group
Open Network Computing
Online Public Access Catalogue
Open Systems Interconnection
Post Office Protocol
Plain Old Telephone Services
Point to Point Protocol
Quality of Service
Reverse Address Resolution Protocol
Resource Discovery Framework
Request For Comment
Routing Information Protocol
Remote Method Invocation
Remote Procedure Call
Security Administrator Tool for Analysing Networks
Standard General Markup Language
Serial Line Internet Protocol
Short Message Service
Simple Mail Transfer Protocol
Simple Network Management Protocol
Standard Query Language
Secure Socket Layer
Transmission Control Protocol
TCP and IP based protocol stack
Trivial File Transfer Protocol
Top Level Domain
Time To Live
User Datagram Protocol
Universal Mobile Telecommunications Services
Uniform Resource Characteristics
Uniform Resource Identifier
Uniform Resource Locator
Uniform Resource Name
Virtual Reality Modeling Language
Wide Area Network
Wireless Application Protocol
Windows, Icons, Menus and Pointers
What You See Is What You Get
World Wide Web
eXtensible HyperText Markup Language
eXtensible Markup Language
eXtensible Stylesheet Language