Useful Terms A-Z

Here are some terms you may come across.




A programming methodology that was developed by Microsoft and can be used to isolate software components and build functions using those components. ActiveX can be used with a variety of programming languages and in an Internet programming environment.

A part that electrically or physically connects a device to a computer or to another device.  A circuit board that adds function to a computer.


An application program, written in the Java programming language, that can be retrieved from a Web server and executed by a Web browser. A reference to an applet appears in the markup for a Web page, in the same way that a reference to a graphics file appears; a browser retrieves an applet in the same way that it retrieves a graphics file. For security reasons, an applet's access rights are limited in two ways: the applet cannot access the file system of the client upon which it is executing, and the applet's communication across the network is limited to the server from which it was downloaded.  

A network protocol developed by Apple Computer, Inc. This protocol is used to interconnect network devices, which can be a mixture of Apple and non-Apple products.

ASCII (American National Standard Code for Information Interchange)  
The standard code, using a coded character set consisting of 7-bit coded characters (8 bits including parity check), that is used for information interchange among data processing systems, data communication systems, and associated equipment. The ASCII set consists of control characters and graphic characters.   


  • In computer security, verification of the identity of a user or the user's eligibility to access an object.  
  • In computer security, verification that a message has not been altered or corrupted.  
  • In computer security, a process used to verify the user of an information system or protected resources.


A set of nodes and their interconnecting links that form a central, high-speed network interconnecting other, typically lower-speed, networks or client nodes.  

In a local area network multiple-bridge ring configuration, a high-speed link to which the rings are connected by means of bridges or routers. A backbone may be configured as a bus or as a ring.  

In a wide area network, a high-speed link to which nodes or data switching exchanges (DSEs) are connected.    


The difference, expressed in hertz, between the highest and the lowest frequencies of a range of frequencies.  

In asynchronous transfer mode (ATM), the capacity of a virtual channel, expressed in terms of peak cell rate (PCR), sustainable cell rate (SCR), and maximum burst size (MBS).  

A measure of the capacity of a communication transport medium (such as a TV cable) to convey data.  

Basic Input/Output System (BIOS) 

Code that controls basic hardware operations, such as interactions with diskette drives, hard disk drives, and the keyboard.

Either of the digits 0 or 1 when used in the binary numeration system.     

A representation of an image by an array of bits.  


A frequency band broad enough to be divided into several narrower bands, each of which can be used for different purposes or be made available to different users.   

A frequency band divisible into several narrower bands so that different kinds of transmission (such as voice, video, and data) can occur at the same time.  

Transmission media and techniques that use a broad frequency range, divided into sub-bands of narrower frequency, so that different kinds of transmission can occur at the same time.  

Broadband LAN

A local area network in which data are encoded, multiplexed, and transmitted with modulation of carriers. A broadband LAN consists of more than one channel.

Transmission of the same data to all destinations.   

Simultaneous transmission of data to more than one destination.  

A routine or storage used to compensate for a difference in rate of flow of data, or time of occurrence of events, when transferring data from one device to another.

A facility for transferring data between several devices located between two end points, only one device being able to transmit at a given moment.   

A computer configuration in which processors are interconnected in series.


A mechanism on a pointing device, such as a mouse, used to request or initiate an action or a process.  

A graphical device that identifies a choice.


A string that consists of a number of bits, treated as a unit, and representing a character.   

A binary character operated upon as a unit and usually shorter than a computer word. 


A special-purpose buffer storage, smaller and faster than main storage, used to hold a copy of instructions and data obtained from main storage and likely to be needed next by the processor.    

A buffer storage that contains frequently accessed instructions and data; it is used to reduce access time.  

An optional part of the directory database in network nodes where frequently used directory information may be stored to speed directory searches.  

To place, hide, or store in a cache.  

Caching proxy server  
A proxy server that stores the documents that it retrieves from other servers in a local cache. The caching proxy server can then respond to subsequent requests for these documents without having to retrieve them from the other servers. This can improve response time.  


Pertaining to the ability to distinguish between uppercase and lowercase letters.


High-capacity read-only memory in the form of a compact disc.    

Central Processing Unit (CPU)  

The part of a computer that includes the circuits that control the interpretation and execution of instructions. A CPU is the circuitry and storage that executes instructions. Traditionally, the complete processing unit was often regarded as the CPU, whereas today the CPU is often a microchip. In either case, the centrality of a processor or processing unit depends on the configuration of the system or network in which it is used.  

In communications, the model of interaction in distributed data processing in which a program at one site sends a request to a program at another site and awaits a response. The requesting program is called a client; the answering program is called a server.

Client workstation 

The client workstation depends on a server workstation to provide it with views and status information.

An area of storage provided by the system to hold data temporarily.  

Coaxial cable  
A cable consisting of one conductor, usually a small copper tube or wire, within and insulated from another conductor of larger diameter, usually copper tubing or copper braid.


Pertaining to adapters that compress and decompress video files. The letters "CODEC" represent "compression/decompression"; in the past, they represented "coder/decoder."

Common Gateway Interface (CGI)   

A standard for the exchange of information between a Web server and computer programs that are external to it. The external programs can be written in any programming language that is supported by the operating system on which the Web server is running.


  1. The process of eliminating gaps, empty fields, redundancies, and unnecessary data to shorten the length of records or blocks.  
  2. Any encoding to reduce the number of bits used to represent a given message or record.

A functional unit that can perform substantial computations, including numerous arithmetic operations and logic operations without human intervention during a run. In information processing, the term computer usually describes a digital computer. A computer may consist of a stand-alone unit or may consist of several interconnected units.   

The capability of a system or device to be attached to other systems or devices without modification.   

The capability to attach a variety of functional units without modifying them.

Information that a Web server stores on a user's computer when the user browses a particular Web site. This information helps the Web server track such things as user preferences and data that the user may submit while browsing the site. For example, a cookie may include information about the purchases that the user makes (if the Web site is a shopping site). The use of cookies enables a Web site to become more interactive with its users, especially on future visits.  


A device that connects a modem to a telephone network.


A movable, visible mark used to indicate a position of interest on a display surface.

A visible indication of the position where user interaction with the keyboard will appear. The keyboard cursors are the selection cursor and the text cursor.


A re-interpretable representation of information in a formalized manner suitable for communication, interpretation, or processing. Operations can be performed upon data by humans or by automatic means.

Any representations such as characters or analog quantities to which meaning is or might be assigned.

A representation of facts or instructions in a form suitable for communication, interpretation, or processing by human or automatic means. Data includes constants, variables, arrays, and character strings.  


A collection of data with a given structure for accepting, storing, and providing, on demand, data for multiple users.

A collection of interrelated data organized according to a database schema to serve one or more applications.

Database Administrator (DBA)

A person who is responsible for a database system, particularly for defining the rules by which data is stored and accessed. Usually, the database administrator is also responsible for database integrity, security, performance, and recovery.    

Data store 

A place (such as a database system, file, or directory) where data is stored.

Data stream 

All information (data and control commands) sent over a data link usually in a single read or write operation.  

A continuous stream of data elements being transmitted, or intended for transmission, in character or binary-digit form, using a defined format.  

Data transfer rate 

The average number of bits, characters, or blocks per unit time passing between corresponding equipment in a data transmission system. The rate is expressed in bits, characters, or blocks per second, minute, or hour.

Corresponding equipment should be indicated; for example, modems, intermediate equipment, or source and sink.  


The inverse of compression.  

In computer security, the process of transforming encoded text into plaintext.  


A graphical user interface (GUI) that enables a user to interact with and perform operations on a computer system.    

Destination address  
A code that identifies the location to which information is to be sent.  

Pertaining to the direction in which a switched connection is requested by any node or terminal other than the receiving host or an NCP.  


The interaction between a user and a computer.  

In an interactive system, a series of related inquiries and responses similar to a conversation between two people.

Pertaining to a network connection that is established by dialing a telephone number.


  • Pertaining to data that consist of digits.   
  • Pertaining to data in the form of digits.   
  • Contrast with analog.  

Digital signature 

In e-commerce, data that is appended to, or is a cryptographic transformation of, a data unit and that enables the recipient of the data unit to verify the source and integrity of the unit and to recognize potential forgery.  

Direct routing
In Internet communications, the transmission of an Internet Protocol (IP) datagram when the destination and the source reside on the same IP network or IP subnet.    

Disk drive 

A diskette drive or a hard disk drive as opposed to a CD-ROM drive.

Display panel  
In computer graphics, a predefined display image that defines the locations and characteristics of display fields on a display surface.

Display station  

An input/output device containing a display screen and an attached keyboard that allows a user to send information to or receive information from the system.

Document type
The type of data in a particular Printing Systems Manager (PSM) document. For example, a print file document contains only printable data, and a print resource document contains only data such as fonts or form definitions that are not printable.

Document type definition (DTD)  

The rules that specify the structure for a particular class of SGML or XML documents. The DTD defines the structure with elements, attributes, and notations, and it establishes constraints for how each element, attribute, and notation may be used within the particular class of documents. A DTD is analogous to a database schema in that the DTD completely describes the structure for a particular markup language.


That part of a computer network in which the data processing resources are under common control.   

Domain controller 

The domain controller is responsible for coordinating and maintaining activities in the domain.  

Domain name server  
In the Internet suite of protocols, a server that responds to queries from clients for name-to-address and address-to-name mappings as well as for other information.

Domain Name System (DNS)
In the Internet suite of protocols, the distributed database system used to map domain names to IP addresses.

Domain operator  
In a multiple-domain network, the person or program that controls operation of resources controlled by one system services control point (SSCP).  


To use a pointing device to move an object. For example, a user can drag a window border to make the window larger.    

Drag and drop
To directly manipulate an object by moving it and placing it somewhere else using a pointing device (such as a mouse).


A peripheral device, especially one that has addressed storage media.  

The mechanism used to seek, read, and write information on a storage medium  


To record, at a particular instant, the contents of all or part of one storage device in another storage device. Dumping is usually for the purpose of debugging.    

To copy data in a readable format from main or auxiliary storage onto an external medium such as tape, diskette, or printer.


Either (a) the transaction of business over an electronic medium such as the Internet or (b) any organization (for example, commercial, industrial, nonprofit, educational, or governmental) that transacts its business over an electronic medium such as the Internet. An e-business combines the resources of traditional information systems with the vast reach of an electronic medium such as the Internet (including the World Wide Web, intranets, and extranets); it connects critical business systems directly to critical business constituencies--customers, employees, and suppliers. The key to becoming an e-business is building a transaction-based Web site in which all core business processes (especially all processes that require a dynamic and interactive flow of information) are put online to improve service, cut costs, and sell products.  

The buying, selling or exchanging of information, goods or services via any an electronic medium such as the Internet.  

Electronic mail (e-mail)
Correspondence in the form of messages transmitted between user terminals over a computer network.    

The generation, transmission, and display of correspondence and documents by electronic means.    

In computer security, the process of transforming data into an unintelligible form in such a way that the original data either cannot be obtained, or can be obtained only by using a decryption process.  

A 10-Mbps baseband local area network that allows multiple stations to access the transmission medium at will without prior coordination, avoids contention by using carrier sense and deference, and resolves contention by using collision detection and delayed retransmission. Ethernet uses carrier sense multiple access with collision detection (CSMA/CD).

Extensible Markup Language (XML)
A standard metalanguage for defining markup languages that was derived from and is a subset of SGML. XML omits the more complex and less-used parts of SGML and makes it much easier to (a) write applications to handle document types, (b) author and manage structured information, and (c) transmit and share structured information across diverse computing systems. The use of XML does not require the robust applications and processing that is necessary for SGML. XML is being developed under the auspices of the World Wide Web Consortium (W3C).  


Fiber optics  
The branch of optical technology concerned with the transmission of radiant power through fibers made of transparent materials such as glass, fused silica, and plastic

An identifiable area in a window. Examples of fields are: an entry field, into which a user can type or place text, and a field of radio button choices, from which a user can select one choice.  

The smallest identifiable part of a record.  


A named set of records stored or processed as a unit  

File name extension  
An addition to a file name that identifies the file type (for example, text file or program file).  

File transfer
The transfer of one or more files from one system to another over a data link    

File Transfer Protocol (FTP)
In the Internet suite of protocols, an application layer protocol that uses TCP and Telnet services to transfer bulk-data files between machines or hosts.  

In communication, a functional unit that protects and controls the connection of one network to other networks. The firewall (a) prevents unwanted or unauthorized communication traffic from entering the protected network and (b) allows only selected communication traffic to leave the protected network.    

A container used to organize objects.

A family of characters of a given size and style; for example, 9-point Helvetica.


Gigabit (Gb)

For processor storage, real and virtual storage, and channel volume, 230 or 1 073 741 824 bits.

For disk storage capacity and communications volume, 1 000 000 000 bits    

Gigabyte (GB)  
For processor storage, real and virtual storage, and channel volume, 230 or 1 073 741 824 bytes.  

For disk storage capacity and communications volume, 1 000 000 000 bytes.


A permanent copy of a display image generated on an output device such as a printer or plotter, and which can be carried away.     

A printed copy of machine output in a visually readable form; for example, printed reports, listings, documents, and summaries.    

Hard disk  
A mass storage medium for computers that is typically available as a fixed disk (such as the disks used in the system units of personal computers or in drives that are external to a personal computer) or a removable cartridge.

Home page
The initial Web page that is returned by a Web site when a user specifies the uniform resource locator (URL) for the Web site. For example, if a user specifies the URL for the IBM Web site, which is, the Web page that is returned is the IBM home page. Essentially, the home page is the entry point for accessing the contents of the Web site. The home page may sometimes be called the "welcome page" or the "front page."  

A computer that is connected to a network (such as the Internet) and provides an access point to that network. Also, depending on the environment, the host may provide centralized control of the network. The host can be a client, a server, or both a client and a server simultaneously.

Host ID
In the Internet suite of protocols, that part of the IP address that defines the host system on the network. The length of the host ID depends on the type of network or network class (A, B, or C).  

In a network, a point at which circuits are either connected or switched. For example, in a star network, the hub is the central node; in a star/ring network, it is the location of wiring concentrators.


A way of presenting information online with connections (called hypertext links) between one piece of information and another.

Hypertext Markup Language (HTML)  
A markup language that conforms to the SGML standard and was designed primarily to support the online display of textual and graphical information that includes hypertext links.  

Hypertext Transfer Protocol (HTTP)  
In the Internet suite of protocols, the protocol that is used to transfer and display hypertext documents.  



A graphic symbol, displayed on a screen, that a user can point to with a device such as a mouse in order to select a particular function or software application.  

A graphical representation of an object (for example, a file or program) that consists of an image, an image background, and a label.

In system development, preparing and placing a functional unit in position for use.     

A particular computing system, including the work it does and the people who manage it, operate it, apply it to problems, service it, and use the results it produces.

Integrated Services Digital Network (ISDN)  
A digital end-to-end telecommunication network that supports multiple services including, but not limited to, voice and data. ISDNs are used in public and private network architectures.  

The worldwide collection of interconnected networks that use the Internet suite of protocols and permit public access.

Internet Protocol (IP)   

In the Internet suite of protocols, a connectionless protocol that routes data through a network or interconnected networks and acts as an intermediary between the higher protocol layers and the physical network.


A private network that integrates Internet standards and applications (such as Web browsers) with an organization's existing computer networking infrastructure.  

IP address
The unique 32-bit address that specifies the location of each device or workstation on the Internet. For example, is an IP address.  

IP router  

A device in an IP internet that is responsible for making decisions about the paths over which network traffic will flow. Routing protocols are used to gain information about the network and to determine the best route over which the datagram should be forwarded toward the final destination. The datagrams are routed based on IP destination addresses.


An object-oriented programming language for portable interpretive code that supports interaction among remote objects. Java was developed and specified by Sun Microsystems, Incorporated.

A platform-independent, software component technology for building reusable Java components called "beans." Once built, these beans can be made available for use by other software engineers or can be used in Java applications. Also, using JavaBeans, software engineers can manipulate and assemble beans in a graphical drag-and-drop development environment.    

Java Development Kit (JDK)  
A software package that can be used to write, compile, debug, and run Java applets and applications.  

A scripting language that resembles Java and was developed by Netscape for use with the Netscape browser.  

Java Virtual Machine (JVM)     

A software implementation of a central processing unit (CPU) that runs compiled Java code (applets and applications).  

A standard format for storing compressed true-color images. "JPEG" represents "Joint Photographic Experts Group," which is the name of the committee that developed this standard format.


The part of an operating system that performs basic functions such as allocating hardware resources.  

kilobyte (KB)

  1. For processor storage, real and virtual storage, and channel volume, 210 or 1024 bytes.
  2. For disk storage capacity and communications volume, 1000 bytes.


Local Area Network (LAN)

  1. A computer network located on a user's premises within a limited geographical area. Communication within a local area network is not subject to external regulations; however, communication across the LAN boundary may be subject to some form of regulation. 
  2. A network in which a set of devices are connected to one another for communication and that can be connected to a larger network. This can be connected in either an Ethernet or Token Ring. A LAN contrasts with a MAN and WAN. 

Log on  
To connect to a computer system or network. Some systems may use the term "log in" or "sign on" for this concept.  


A computer, usually in a computer center, with extensive capabilities and resources to which other computers may be connected so that they can share facilities.

The process of converting data that is transmitted in one format by the sender into the data format that can be accepted by the receiver.  

The identification of the components of a document to enable each component to be appropriately formatted, displayed, or used.  

Markup language
A notation for identifying the components of a document to enable each component to be appropriately formatted, displayed, or used.

Megabit (Mb)  
For processor storage, real and virtual storage, and channel volume, 220 or 1 048 576 bits.  

For disk storage capacity and communications volume, 1 000 000 bits.  

Megabyte (MB)
For processor storage, real and virtual storage, and channel volume, 220 or 1 048 576 bytes.  

For disk storage capacity and communications volume, 1 000 000 bytes.  

All of the addressable storage space in a processing unit and other internal storages that is used to execute instructions.   


A list of options displayed to the user by a data processing system, from which the user can select an action to be initiated.   

In text processing, a list of choices displayed to the user by a text processor from which the user can select an action to be initiated.   

A list of choices that can be applied to an object. A menu can contain choices that are not available for selection in certain contexts. Those choices are indicated by reduced contrast.  

Menu bar  
The area near the top of a window, below the title bar and above the rest of the window, that contains choices that provide access to other menus.  

In the AIX operating system, a rectangular area at the top of the client area of a window that contains the titles of the standard pull-down menus for that application.  

Metropolitan Area Network (MAN)  
A network formed by the interconnection of two or more networks which may operate at higher speed than those networks, may cross administrative boundaries, and may use multiple access methods. Contrast with LAN and WAN.  


In VM, a direct access storage device or a logical subdivision of a direct access storage device that has its own virtual device number, consecutive virtual cylinders (starting with virtual cylinder 0), and a volume table of contents (VTOC) or disk label identifier.  

Modem (modulator/demodulator)
A functional unit that modulates and demodulates signals. One of the functions of a modem is to enable digital data to be transmitted over analog transmission facilities.

A device that converts digital data from a computer to an analog signal that can be transmitted on a telecommunication line, and converts the analog signal received to data for the computer.

A device that observes and records selected activities within a data processing system for analysis. Possible uses are to indicate significant departure from the norm, or to determine levels of utilization of particular functional units.     

Software or hardware that observes, supervises, controls, or verifies operations of a system.     

The function required to initiate the transmission of a token on the ring and to provide soft-error recovery in case of lost tokens, circulating frames, or other difficulties. The capability is present in all ring stations.  

Software that monitors specific applications or the systems on which the applications rely. Monitors typically monitor information such as available disk space or application errors and compare the information to defined thresholds. When thresholds are exceeded, either system or network administrators can be notified, or an automated response can be performed.  

A commonly used pointing device that contains one or more buttons with which a user can interact with a computer system. For example, using a mouse button, a user can select objects or choices, initiate actions, or directly manipulate objects.


A mode of operation that provides for concurrent performance, or interleaved execution of two or more tasks.   



  • An arrangement of nodes and connecting branches.
  • A configuration of data processing devices and software connected for information interchange.
  • A group of nodes and the links interconnecting them.  

In object-oriented design or programming, a concrete realization of a class that consists of data and the operations associated with that data.  

An item that a user can manipulate as a single unit to perform a task. An object can appear as text, an icon, or both.

Open Database Connectivity (ODBC)  
A standard application programming interface (API) for accessing data in both relational and non-relational database management systems. Using this API, database applications can access data stored in database management systems on a variety of computers even if each database management system uses a different data storage format and programming interface.  


Radio button     

A circle with text beside it. Radio buttons are combined to show a user a fixed set of choices from which the user can select one. The circle becomes partially filled when a choice is selected  

Random Access Memory (RAM)  
A temporary storage location in which the central processing unit (CPU) stores and executes its processes.  

Pertaining to data that can be read but cannot be modified.  

Read-Only Memory (ROM)  
Memory in which stored data cannot be modified by the user except under special conditions.  

Relational database  
A database in which the data is organized and can be accessed according to relations.     

Response time  
The elapsed time between the end of an inquiry or demand on a computer system and the beginning of the response; for example, the length of time between an indication of the end of an inquiry and the display of the first character of the response at a user terminal.

For response time monitoring, the time from the activation of a transaction until a response is received, according to the response time definition coded in the performance class.  

Ring network  
A network in which every node has exactly two branches connected to it and in which there are exactly two paths between any two nodes.    

A network configuration in which devices are connected by unidirectional transmission links to form a closed path.  

An ordered sequence of nodes and transmission groups (TGs) that represent a path from an origin node to a destination node traversed by the traffic exchanged between them.

The path that network traffic uses to get from source to destination.  

A computer that determines the path of network traffic flow. The path selection is made from several paths based on information obtained from specific protocols, algorithms that attempt to identify the shortest or best path, and other criteria such as metrics or protocol-specific destination addresses.  

An attaching device that connects two LAN segments, which use similar or different architectures, at the reference model network layer.  

Run time     

The time period during which a computer program is executing. A run-time environment is an execution environment.  


A device that examines a spatial pattern one part after another, and generates analog or digital signals corresponding to the pattern. Scanners are often used in mark sensing, pattern recognition, or character recognition.   

For the 3725 communication controller, a processor dedicated to controlling a small number of telecommunication lines. It provides the connection between the line interface coupler hardware and the central control unit.

Scripting language
The programming language in which a script is written.

Secure Sockets Layer (SSL)
A security protocol that provides communication privacy. SSL enables client/server applications to communicate in a way that is designed to prevent eavesdropping, tampering, and message forgery. SSL was developed by Netscape Communications Corp. and RSA Data Security, Inc

A portion of a computer program that may be executed without the entire computer program being resident in main storage.     

A group of display elements.  

A section of cable between components or devices. A segment may consist of a single patch cable, several patch cables that are connected, or a combination of building cable and patch cables that are connected.  

In Internet communications, the unit of transfer between TCP functions in different machines. Each segment contains control and data fields; the current byte-stream position and actual data bytes are identified along with a checksum to validate received data.  


A functional unit that provides services to one or more clients over a network. Examples include a file server, a print server, and a mail server.

SET Secure Electronic Transaction
A specification for securing payment card transactions over open networks such as the Internet. SET was developed by Visa, MasterCard, IBM, and other technology companies.

Simple Mail Transfer Protocol (SMTP)

In the Internet suite of protocols, an application protocol for transferring mail among users in the Internet environment. SMTP specifies the mail exchange sequences and message format. It assumes that the Transmission Control Protocol (TCP) is the underlying protocol.


An endpoint provided by the transport service of a network for communication between processes or application programs.

Socket address

The address of an application program that uses the socket interface on the network. In Internet format, it consists of the IP address of the socket's host and the port number of the socket. The application program is usually not aware of the structure of the address.


A programming language that is used to define and manipulate data in a relational database.

An input or output point of a system that uses telecommunication facilities; for example, one or more systems, computers, terminals, devices, and associated programs at a particular location that can send or receive data over a telecommunication line.


A functional unit into which data can be placed, in which they can be retained and from which they can be retrieved.    The action of placing data into a storage device.   


In TCP/IP, a part of a network that is identified by a portion of the IP address.


Pertaining to two or more processes that depend upon the occurrence of specific events such as common timing signals. Occurring with a regular or predictable time relationship.


In the Internet suite of protocols, a protocol that provides remote terminal connection service. It allows users of one host to log on to a remote host and interact as directly attached terminal users of that host.


An event that occurs at the end of a predetermined period of time that began at the occurrence of another specified event.  A time interval allotted for certain operations to occur; for example, response to polling or addressing before system operation is interrupted and must be restarted.

Title bar
The area at the top of each window that contains the system-menu symbol, a small icon, a window title, and the maximize, minimize, and restore buttons.

Token-bus network

A bus network in which a token passing procedure is used.

Token passing
In a token-ring network, the process by which a node captures a token; inserts a message, addresses, and control information; changes the bit pattern of the token to the bit pattern of a frame; transmits the frame; removes the frame from the ring when it has made a complete circuit; generates another token; and transmits the token on the ring where it can be captured by the next node that is ready to transmit.

Token-ring network
A ring network that allows unidirectional data transmission between data stations, by a token passing procedure, such that the transmitted data return to the transmitting station.  A network that uses a ring topology, in which tokens are passed in a circuit from node to node. A node that is ready to send can capture the token and insert data for transmission.


In communications, the physical or logical arrangement of nodes in a network, especially the relationships among nodes and the links between them.

Transmission Control Protocol (TCP)
A communications protocol used in the Internet and in any network that follows the Internet Engineering Task Force (IETF) standards for internetwork protocol. TCP provides a reliable host-to-host protocol between hosts in packet-switched communications networks and in interconnected systems of such networks. It uses the Internet Protocol (IP) as the underlying protocol.

Transmission Control Protocol/Internet Protocol (TCP/IP)
The Transmission Control Protocol and the Internet Protocol, which together provide reliable end-to-end connections between applications over interconnected networks of different types.

The suite of transport and application protocols that run over the Internet Protocol.

Tree network 

A network in which there is exactly one path between any two nodes

Tree structure

A data structure that represents entities in nodes, with at most one parent node for each node, and with only one root node.


Uniform resource locator (URL)

A sequence of characters that represent information resources on a computer or in a network such as the Internet. This sequence of characters includes (a) the abbreviated name of the protocol used to access the information resource and (b) the information used by the protocol to locate the information resource. For example, in the context of the Internet, these are abbreviated names of some protocols used to access various information resources: http, ftp, gopher, telnet, and news; and this is the URL for the IBM home page: The address of an item on the World Wide Web. It includes the protocol followed by the fully qualified domain name (sometimes called the host name) and the request. The Web server typically maps the request portion of the URL to a path and file name. For example, if the URL is, the protocol is http; the fully qualified domain name is; and the request is /e-business/info/.

Any person or any thing that may issue or receive commands and messages to or from the information processing system.

Anyone who requires the services of a computing system.

Virtual address 

The address of a location in virtual storage. A virtual address must be translated into a real address in order to process the data in processor storage.

Virtual store

An interactive simulation of a store on the World Wide Web.

Visual Basic Script (VBScript)   

A scripting language that was developed by Microsoft for use with the Internet Explorer browser.


Web browser
A client program that initiates requests to a Web server and displays the information that the server returns.

The person who is ultimately responsible for managing and maintaining a particular Web site.

Web page
Any document that can be accessed by a uniform resource locator (URL) on the World Wide Web. A server that is connected to the Internet and is dedicated to serving Web pages.

Web site  

A Web server that is managed by a single entity (an organization or an individual) and contains information in hypertext for its users, often including hypertext links to other Web sites. Each Web site has a home page. In a uniform resource locator (URL), the Web site is indicated by the fully qualified domain name. For example, in the URL the Web site is indicated by, which is the fully qualified domain name.

Wide Area Network (WAN)
A network that provides communication services to a geographic area larger than that served by a local area network or a metropolitan area network, and that may use or provide public communication facilities.

A data communication network designed to serve an area of hundreds or thousands of miles; for example, public and private packet-switching networks, and national telephone networks.


Zone Information Protocol (ZIP)
In AppleTalk networks, a protocol that provides zone management service by maintaining a mapping of the zone names and network numbers across the internet on the session layer.

In a user interface, to progressively increase or decrease the size of a part of an image on a screen or in a window.