V.24
An International Telecommunication Union specification defining interchange circuits between data terminal and data communications equipment (for example, between a PC and a modem). V.24 is equivalent to the RS-232 specification (see RS-232).

V.35
An International Telecommunication Union interface specification for data transmitted at 48 kilobits per second.

VAN (value-added network)
A private network through which value-added carriers provide special data transmission services.

VAR (value-added reseller)
An organization that buys equipment from a vendor at a discount, adds value (such as application software packaged and sold with underlying system software) and remarkets it.

VAS (value-added service)
A service offered by a network or its resellers that generates additional revenue by offering increased benefits to its subscribers.

VAX (Virtual Address Extension)
The Digital Equipment architecture that was the company's principal product line prior to the Alpha. VAX was enormously successful in Digital's traditional engineering and scientific customer base and, more significantly, enabled Digital to penetrate the commercial data-processing and office-automation markets. In 1999, Compaq Computer — which acquired Digital Equipment in 1998, and was itself acquired by Hewlett-Packard in 2002 — announced plans to phase out the VAX platform in favor of Alpha system products.

VB (Visual Basic)
A high-level programming language from Microsoft.

VBA (Visual Basic for Applications)
A version of Microsoft's Visual Basic used to create basic and customized programs.

VBR (variable bit rate)
An asynchronous transfer mode (ATM) quality of service category, defined by the ATM Forum. Both real-time variable bit rate (rt-VBR) and non-real-time variable bit rate (nrt-VBR) are defined. Apart from the traffic parameters for peak cell rate and sustainable cell rate (which defines the average bit rate required by the application), additional quality-of-service parameters — such as maximum cell transfer delay, cell delay variation and maximum burst size — must be agreed on. The typical application for which it is used is compressed voice and videoconferencing for rt-VBR, and response-time-sensitive data such as Systems Network Architecture (SNA) for nrt-VBR.

VBScript
A Microsoft proprietary language derived from Visual Basic. Like JavaScript, VBScript is intended for use as a browser-based, server-side and administrative language. Unlike JavaScript, support for VBScript in browsers is limited to Microsoft's Internet Explorer.

VBUG (Voice Browser Usability Group)
A group within the World Wide Web Consortium (W3C) developing voice portal usability guidelines and best practices. See voice browser, voice portal and W3C.

VC (virtual channel)
In asynchronous transfer mode (ATM), a communications track between two nodes giving the bandwidth needed for a virtual connection across the network.

VCR (videocassette recorder)
A device that records and plays videocassettes, typically used in conjunction with a television set.

VDSL (very high-speed digital subscriber line)
Extremely high-speed digital subscriber line (DSL) connections over short distances.

vendor-neutral
A state in which no one vendor can control the definition, revision or distribution of a specification. Vendor-neutral specifications encourage the development of competing yet compatible implementations, freeing the purchaser to choose from a multitude of vendors without suffering a loss of functionality.

VEP (vertical enterprise portal)
A portal that typically includes a business application and focuses on a specific business function (e.g., investment or customer service) of an enterprise — unlike a horizontal enterprise portal (HEP), which serves a broad enterprise population. See portal and HEP.

Veronica
A former Internet search tool that used descriptive text; a precursor to today's Web search engines.

vertical portal
A portal that provides content aggregation relevant to a specific industry, links to related sites, collaboration capabilities and e-commerce services for relevant products and services.

VF (voice frequency)
Any frequency within the audio-frequency range that is essential for the transmission of speech of commercial quality — that is, 300 hertz (Hz) to 3,000 Hz.

VGA (Video Graphics Array)
A hardware display and software resolution standard for personal computers.

VHDL (VHSIC Hardware Description Language)
An industry standard format for describing very high-speed integrated circuit (VHSIC) logic and behavior. See VHSIC.

VHF (very high frequency)
The range of radio frequencies between 30 and 300 megahertz.

VHS (video home system)
A videocassette format.

VHSIC (very high speed integrated circuit)
A category of integrated circuit (IC) technology. See IC.

VICS (Voluntary Interindustry Commerce Standards)
A committee dedicated to the adoption of bar coding and electronic data interchange (EDI) in the department store and mass merchandise industries. It has established collaborative planning, forecasting and replenishment (CPFR) standards for the consumer goods industry that are published by the Uniform Code Council (UCC). See CPFR, EDI and UCC.

videoconferencing
Communication by individuals or groups using systems that support image, voice and data transfer over digital networks or telephone circuits. Videoconferencing systems can take the form of large, dedicated units for group meetings or can be integrated with desktop personal computers.

video server
A server that delivers streams of digital video and audio.

video signal
A signal comprising frequencies normally required to transmit pictorial information.

VIM (Vendor Independent Messaging)
An application programming interface (API) developed to support the exchange of electronic mail among programs from different vendors. See API.

Vines
A network operating system (NOS) developed by Banyan Systems (now ePresence). See NOS.

virtual circuit
In packet switching, network facilities that appear to users to be an end-to-end circuit, but are in fact a dynamically variable network connection in which sequential user data packets may be routed differently during the course of a "virtual connection." Transmission facilities may be shared by many virtual circuits simultaneously.

virtual classroom
An online location where a course can be experienced. An instructor may lead or facilitate the learning event, while students can merely participate or collaborate with one another. These activities may occur synchronously or asynchronously. Virtual-classroom functionality is similar to that used for conferencing, chat rooms, and other forums in which participants exchange comments or engage in other online interactions.

virtual enterprise
An enterprise integrating several ideals: outsourced noncore competencies; a focus on core business strengths; little or no physical presence or infrastructure; a network of business alliances; the exploitation of intellectual capital; and a heavy reliance on telecommunications. Virtual enterprises have outsourced the physical processes and administrative attributes of traditional business, and have expanded and combined intellectual activities (e.g., problem solving) with standard business processes such as marketing.

virtual reality
A computerized process, usually including special equipment, that projects the user into a simulated three-dimensional space. It gives the user the sensation of being in the simulated environment and the ability to respond to the simulation.

virtual storage
A feature that makes a computer appear to have a much larger memory than its real memory. This is accomplished by software that moves pages rapidly in and out of a high-speed, random-access storage device, usually a disk.

virus
Software used to infect a computer. After the virus code is written, it is buried within an established program. Once that program is executed, the virus code is activated and attaches copies of itself to other programs in the system. Infected programs copy the virus to other programs.

visualization
A technique used to illustrate information objects and their relationships on a display. Strategic visualization graphically illustrates the strength of relationships by the proximity of objects on the display. Advanced technology can make a significant difference in users' ability to interface to large knowledge repositories. These advances use the distance between objects on the display to reflect the similarity of meaning, similarity of content or other relationships (such as association with a group).

Visual J++
A Microsoft variant of the Java language.

Visual Studio
A Microsoft package of several application development (AD) tools with complementary, albeit overlapping, focuses, including Visual Basic, Visual C++ and Visual J++.

VLA (Volume License Agreement)
A software licensing option offered under the Novell "Customer Connections" program, with an entry point that opens discounts to smaller organizations.

VLAN (virtual local-area network)
A set of systems that, regardless of higher-layer addressing or location, is designated as a logical local-area network (LAN) and treated as a set of contiguous systems on a single LAN segment. VLANs can be proprietary or standardized using the Institute of Electrical and Electronics Engineers' 802.1q specification. Typical grouping parameters for VLANs include the port number of the hub, switch or router, the higher-layer protocol such as Internet Protocol (IP) or Internetwork Packet Exchange (IPX), the Media Access Control (MAC) address, and the traditional subnet. The goal of VLANs is to provide simpler administration and partitioning at the MAC layer. See LAN, IP and IPX.

VLDB (very large database)
A database greater than 100 gigabytes.

VLIW (very long instruction word)
A processor architecture in which each data word contains multiple instructions. Used in Intel's next-generation IA-64 products.

VLSI (very large-scale integration)
A technology that makes it possible to place the equivalent of between 100,000 and 1 million transistors on a chip.

VM (virtual machine)
A software implementation of a hardware-like architecture, which executes predefined instructions in a fashion similar to a physical central processing unit (CPU). A VM can be used to create a cross-platform computing environment that loads and runs on computers independently of their underlying CPUs and operating systems. A notable example is the Java Virtual Machine, the environment created on a host computer to run Java applets. Although VMs have existed longer than Java, Java has made VMs highly visible (see Java).

VM (Virtual Machine)
An IBM mainframe operating-system environment. VM manages a system so that all its resources — processors, storage and input/output devices — are available to many users at the same time. Each user has at his disposal the functional equivalent of a real dedicated system. Because this functional equivalent is simulated by VM and does not really exist, it is called a "virtual" machine.

VMI (vendor-managed inventory)
In the VMI process, the vendor assumes responsibility for managing the replenishment of a customer's stock. Rather than a customer submitting orders, the vendor will replenish stock as needed. This is sometimes referred to as supplier-managed or co-managed inventory.

VMS (Virtual Memory System)
A mainframe operating system developed by Digital Equipment (later acquired by Compaq Computer, which in turn was acquired by Hewlett-Packard).

vocabulary-based transformation
A sophisticated form of transformation that leverages pre-built vocabularies to enable semantic adjustments including, but not limited to, synonyms. An abstract or conceptual vocabulary (or taxonomy or ontology) is the definition of a set of terms (both elementary and composite), their structural relationships and their constraints in a metadata-independent manner. See transformation.

VOD (video on demand)
A multimedia application with which a user can access motion or still video, which may be available as public or private services.

VoD (voice over data)
Transmission of voice communication over a data network.

VoFR (voice over frame relay)
Transmission of voice communications over a frame relay data network.

VOI (value on investment)
An approach that sets out to measure the total business value derived from an initiative — including "soft" benefits as well as "hard" financial returns.

voice browser
A system that allows telephone access to voice portal sites. It prepares and presents information to callers, interprets their commands and enables them to navigate the site. Architectures and implementations vary, but many will use VoiceXML or a similar protocol to access the portal application. See voice portal and VoiceXML.

voice grade
A category of communications where bandwidth is equivalent to that of a telephone line obtained through the public telephone network. The maximum potential bandwidth of a voice-grade channel is approximately 20 kilohertz; however, most voice grade channels in a transmission facility are usually spaced 4,000 hertz apart, and not all of that bandwidth is generally available to a user due to the presence of noise-limiting loading coils. The telephone network itself is usually defined in terms of channels, with frequencies from 300 to 3,400 hertz.

voice mail
A service providing digitized voice message handling (also known as "voice messaging"). Voice mail systems enable users to send, receive, and redirect voice messages through office telephone systems and computers.

voice portal
A system that uses advanced speech recognition technology to provide phone access to information on the Internet. Key components of most voice portals include:

Optional components include software to support context-sensitive, personalized assistance and support for VoiceXML. See voice browser and VoiceXML.

VoiceXML (Voice Extensible Markup Language)
A voice-technology-based version of Extensible Markup Language (XML) supported by more than 200 companies. Created by AT&T, IBM, Lucent and Motorola, it is now a specification of the World Wide Web Consortium. See voice browser, voice portal and XML.

VoIP (voice over IP)
Transmission of voice communications over Internet Protocol (IP) data networks, such as IP-based LANs, intranets or the Internet. Many carriers offer integrated services such as voice and data over a single "pipe." However, VoIP still poses several concerns such as voice quality, traffic congestion, slow acceptance of standards, regulatory ambiguity and potential lack of future demand.

VP (virtual path)
In asynchronous transfer mode (ATM), the bandwidth between two points on a network used by one or more virtual channels.

VPA (volume purchase agreement)
An agreement between a computer vendor and a customer under which the vendor grants discounted prices in return for the customer's commitment to purchase a minimum quantity of products.

VPIM (Voice Profile for Internet Mail)
A protocol for the deployment of digital voice mail networking over the Internet.

VPN (virtual private network)
A system that delivers private communications services on a shared, public-network infrastructure, and provides customized operating characteristics uniformly and universally across an enterprise. The term "VPN "is generically used to refer to voice VPNs. To avoid confusion, those used for data, rather than voice, communications are more properly referred to as "data VPNs" or "IP VPNs." VPN service providers define a VPN as a wide-area network of permanent virtual circuits, generally using asynchronous transfer mode or frame relay to transport IP. VPN technology providers often define "virtual private networking" as the use of encryption software or hardware to bring privacy to communications over a public or untrusted data network.

VRAM (video random-access memory)
A type of dynamic random access memory (DRAM) used in high-speed processing of visual data. See DRAM.

VRML (Virtual Reality Modeling Language)
A means of rendering 3-D worlds from mathematical equations or descriptions. A VRML browser can create shapes and text within a navigable 3-D context. The v.2.0 specifications further enhance the immersive experience, allowing for such real-world events as interaction between "visitors" and collision detection when a user "bumps into" an object or other users.

VRRP (Virtual Router Redundancy Protocol)
A network protocol that enables the same virtual Internet Protocol (IP) address to be used by several routers in an IP network — one of which acts as the master router, with the others acting as backups in case the master fails. Specifications for the protocol are defined and developed by the VRRP Working Group of the Internet Engineering Task Force.

VRU (voice response unit)
An automated telephone answering system (also known as a voice response system) consisting of hardware and software that allows the caller to navigate through a series of prerecorded messages and use a menu of options through the buttons on a touch-tone telephone or through voice recognition.

VSAM (Virtual Storage Access Method)
IBM's access method for direct-access files. It is optimized for a virtual storage environment. Multiple Virtual Storage (MVS), Information Management System (IMS), Customer Information Control System (CICS) and DB2 all use VSAM. See DB2, CICS, IMS and MVS.

VSAT (very small aperture terminal)
A satellite-based networking service that has a low per site cost ($175 per month per site or less). VSATs achieved their low cost by using shared, high-power satellite capacity, asymmetric data flows and a star topology — enabling remote "earth stations" at the sites to be as inexpensive as $5,000 (including installation). VSAT economies improve as the number of remote or branch sites increase; a VSAT network may connect hundreds or thousands of branch sites to a central site.

VSE (Virtual Storage Extended)
A multitasking, 370-architected IBM operating system akin to Multiple Virtual Storage (MVS). VSE work runs in partitions rather than address spaces, but is largely similar to MVS. See MVS.

VTAM (Virtual Telecommunications Access Method)
The main Systems Network Architecture (SNA) subsystem resident in an IBM mainframe that manages session establishment and data flow between terminals and application programs, or between application programs. See SNA.

VTS (virtual tape subsystem)
Tape library hardware and software extensions that utilize direct-access storage device (DASD) buffers to multiply the tape device count, throughput and storage density of tape library systems. See DASD.

V.x series
A series of International Telecommunication Union specifications pertaining to the connection of digital equipment to the public switched telephone network (see V.24 and V.35).