Fallback: When it's made available, a fallback is what's provided as a possibly acceptable compromise solution if a main function, eg in a PC or communication path, fails to work.

Favourites: Bookmarks (qv) of URLs that are called thus in MS Internet Explorer browsers.

FDD: See: Floppy Disk Drive.

Fiber Distributed Data Interface (FDDI): A high-speed (100Mb/s) LAN standard (also known as 100BaseT). The underlying medium is fiber optics, and the topology is a dual-attached, counter-rotating token ring. See also: Local Area Network, Token ring.

File transfer: The copying of a file from one computer to another over a computer network. See also: File Transfer Protocol, Kermit.

File Transfer Protocol (FTP): A protocol which allows a user on one host (qv) to access and transfer files to and from another host over a network. An FTP Client is usually the program a User invokes to execute this protocol. See also: Anonymous FTP.

Firewall: A software firewall is provided by a software Application (qv) installed on a PC; it is a barrier between the PC [or network (qv)] and the Internet and wide-ranging controls allow the PC User to limit incoming and outgoing communications, the objective being to prevent unwanted intrusions and outgoing communications. A hardware firewall [which is normally included in a router (qv) but can be stand-alone] blocks or permits selected (incoming only) communications to selected ports on a network (qv).

Firmware: Firmware (as opposed to software) refers to hardware-based program instructions burned into Read-Only Memory (qv), which can't be changed during normal operation. In a PC, the Built-In Operating System (qv) comprising firmware-based program instructions are invoked automatically during boot-up to perform essential self-test, initialisation and system operations.

Flame: A strong opinion and/or criticism of something, usually as a frank inflammatory statement in an electronic mail message. 'Flame wars' occur in tit-for-tat 'flaming' scenarios. See also: Electronic mail.

Floppy Disk Drive (FDD): The transportable media recorder/player fitted as standard on the original and current PCs. Less use is being made now of the good old floppy, since the introduction of other higher capacity media types, such as Zip disks, CDs and DVDs, but it is still essential for moving small files around and for loading rescue files in a crippled PC.

Folders: In PC memories, folders hold files and/or other folders within a hierarchy which is partly predetermined (eg the first level of folders in the 'Desktop' folder and a top level folder for each installed Application (qv) in the Program Files folder) and partly determined by the User (eg new sub-folders to any number of lower levels, particularly for holding User-created files in the 'My Documents' folder).

Font: The type and style of text letters and characters you see in documents, web pages and graphical images of words (images that look like they're typed or written). There are many font choices available to choose from (for example, Helvetica, Times New Roman and Courier New). On hard copy, Courier New looks like it was produced by an old-fashioned typewriter, Helvetica (or Arial/Verdana)) is a good choice for clean-looking headings and Times New Roman is a good choice for distinctive body text. On a computer monitor, however, the 'tails' used in Times New Roman are often not clearly visible, so Helvetica (or Arial/Verdana) tends to be the universal choice (for both headings and body text) of the professional designers (look at all the Help pages in the main Applications). Having said that, some people use funky font styles to express themselves.

Form: A part of a web page that accepts user input. With an online form, you can usually input comments, order products, sign up for newsletters or search for information. At the bottom of a form, you will usually see 'Submit' and 'Reset' buttons; these allow Users to either send the information or clear out the form and start over.

Fragment: A piece of a Packet (qv). When a Router (qv) is forwarding an IP packet to a network that has a maximum packet size smaller than this packet, it is forced to break it up into multiple fragments. These fragments will be reassembled by the IP layer at the destination host.

Fragmentation: The IP process in which a packet is broken into smaller pieces to fit the requirements of a physical network over which the packet must pass. See also: Reassembly.

Frames/Framesets: A method of coding a Web page to divide the layout into two or more independent parts. Technically, it is the simultaneous loading of two or more Web pages within the same browser screen. For certain kinds of content frames are an excellent way to organize information on a Web site.

FTP/FTP Client: See: File Transfer Protocol.

Fully Qualified Domain Name (FQDN): An FQDN is the full name of a system, rather than just its hostname. For example, 'venera' is a hostname and 'venera.isi.edu' is an FQDN. See also: Hostname, Domain Name System.

Gateway: The term 'router' superceded the original definition of 'gateway'. Currently, a gateway is a communications device/program which passes data between networks having similar functions but dissimilar implementations. This should not be confused with a protocol converter. By this definition, a router is a layer 3 (network layer) gateway, and a mail gateway is a layer 7 (application layer) gateway. See also: Mail gateway, Router, Protocol converter.

Geek: A popular term used to describe a person who knows a lot about computers and/or the Internet. In the past, it was considered somewhat derogatory to call someone a geek, but now that the Internet has made computer usage mainstream, even computer savvy people affectionately call themselves geeks.

Giga: Prefix to denote one billion, as in gigabyte.

Gopher: A distributed information service that makes available hierarchical collections of information across the Internet. Gopher uses a simple protocol that allows a single Gopher client to access information from any accessible Gopher server, providing the user with a single "Gopher space" of information. Public domain versions of the client and server are available. See also: Archie, Archive site.

Graphics: Pictures or still images generated on a computer. There are two basic types of computer-generated graphics: object-oriented (vector) graphics and bitmapped (raster) graphics. Graphics may also be short for graphic arts, including the creation, modification, and printing of visual works.

Hacker: A person who manages to invade to privacy of other peoples' computers without their knowledge, normally via the Internet.

Hard copy: A printed copy of some kind of information (as opposed to an electronic version).

Hard Disk Drive: A magnetic data storage medium in a PC, on which all of the PC's software and data is stored. It is one of the most important components in a PC.

Hardware: The physical components (microprocessor, memory, peripherals, etc) that makes up a computer system, as opposed to the software (qv) and the hardware-hosted firmware (qv) components managing the functions performed by this hardware.

HCI: See Human Computer Interface.

HDD: See Hard Disk Drive.

HDTV: See High Definition TeleVision.

Header: The portion of a packet, preceding the actual data, containing source and destination addresses, and error checking and other fields. A header is also the part of an electronic mail message that precedes the body of a message and contains, among other things, the message originator, date and time. See also: Electronic Mail, Packet.

Heat sink: A metal mass with fins designed to absorb heat from a 'busy' and therefore hot device, eg the microprocessor in a PC, for which a small fan helps the process, and radiate this heat away safely into the ambient air.

Hertz: A unit of measurement for electrical vibration, one Hz is equal to one cycle per second. For example, in the UK, the common household electrical supply is at 50 hertz (meaning that the current changes direction or polarity 100 times, or 50 cycles, per second).

Hierarchical routing: The complex problem of routing on large networks can be simplified by reducing the size of the networks. This is accomplished by breaking a network into a hierarchy of networks, where each level is responsible for its own routing. The Internet has, basically, three levels: the backbones, the mid-levels, and the stub networks. The backbones know how to route between the mid-levels, the mid-levels know how to route between the sites, and each site (being an autonomous system) knows how to route internally. See also: Autonomous System, Stub network, Transit network.

High Definition TeleVision (HDTV): The current TV scenario, eg digital transmissions (which are expected to replace the old analogue transmissions in a few years), DVDs, wide screens and electronic file formats such as MPEG 4 and avi, taking more account of the human eye's ability to perceive differences in colour, intensity and refresh rate, etc.

High Performance Computing and Communications (HPCC): High performance computing encompasses advanced computing, communications, and information technologies, including scientific workstations, supercomputer systems, high speed networks, special purpose and experimental systems, the new generation of large scale parallel systems, and application and systems software with all components well integrated and linked over a high speed network.

High Performance Parallel Interface (HIPPI): An ANSI standard which extends the computer bus over fairly short distances at speeds of 800 and 1600 Mb/s. HIPPI is often used in a computer room to connect a supercomputer to routers, frame buffers, mass-storage peripherals, and other computers. See also: American National Standards Institute.

Highway/bus: A term for each of the electrical pathways along which signals are sent from one place to another. A backbone (qv) is a network bus that connects all computers into a single network. In a PC there is a data bus, an address bus, a control bus, an expansion bus and external buses (to which you can attach peripherals or additional devices). These buses include parallel, serial and USB ports, PCI (qv) slots, and SCSI (qv) ports.

HIPPI: See: High Performance Parallel Interface.

Home or Home page: The first page or front page of a website. It serves as the starting point for navigation (not be confused with a buffer page, doorway page, or splash page).

Hop: A term used in routing. A path to a destination on a network is a series of hops, through routers, away from the origin.

Host: A computer that allows users to communicate with other host computers on a network. Individual users communicate by using application programs, such as electronic mail (qv), Telnet (qv) and File Transfer Protocol (qv).

Host name: The unique name by which a computer is known on a network. It is used to identify the Host (qv) in e-mail, Usenet news, or other forms of electronic information interchange.

HPCC: See: High Performance Computing and Communications.

HTML: HyperText Mark-up Language. The tag-based language used in web pages. Similar enough to 'HTTP' to keep you on your toes, don't you think?

HTML Editor: Any software Application that can be used offline to manually insert and edit HTML (and JavaScript, etc) code in a web page, eg Notepad, Dreamweaver, FrontPage.

HTTP: HyperText Transfer Protocol. The main communication protocol (not a language) that is used for the transfer of data from one URL to another on the Internet, as identified at the head of these URLs (http://etc.etc).

Hub: A device used to expand a single interface from a device to several other devices. In ARCnet, a hub is used to connect several computers together. In a message handling service, a hub is used for the transfer of messages across the network.

Human Computer Interface (HCI): The hardware, software and physical arrangement allowing an Operator to interact with a processor.

Hyperlinks: The text or graphics on a web page that can be clicked on with a mouse to take you to another web page or a different area of the same web page. Hyperlinks are usually created (or coded) in HTML. They are also used to load multimedia files, such as AVI movies and AU sound files.

IANA: See: Internet Assigned Numbers Authority.

ICANN: See Internet Corporation for Assigned Names and Numbers (ICANN).

ICMP: See: Internet Control Message Protocol.

Identity theft: Crimes that range from stealing someone's credit card number, eg by hacking a PC, to concocting phony personas, complete with credit reports and college degrees. See also: Hacking.

IEEE: Institute of Electrical and Electronics Engineers.

Inkjet printer: A personal printer in which ink jets are supplied by replaceable ink cartridges. Such printers are popular because of their low initial cost, but running costs are high, unless you have an Epson printer and a source of very cheap 'alternative' replacement cartridges. See also: Laser printer.

Installation: An installed system or the process of placing (and configuring) a program or application onto a computer system. Usually, whether you install by CD-ROM or by download, an installation wizard will help you configure the program for use. For PC users, it is best to begin an installation by going into your Control Panel and then selecting 'Add/Remove Programs'.

Integrated Services Digital Network (ISDN): A technology offered by the telephone carriers of the world. ISDN combines voice and digital network services in a single medium, making it possible to offer customers (dial-up narrowband) digital data services as well as voice connections through a single wire. The standards that define ISDN are specified by CCITT. See also: DSL, CCITT.

International Organization for Standardization (ISO): A voluntary, non-treaty organization founded in 1946 which is responsible for creating international standards in many areas, including computers and communications. Its members are the national standards organizations of the 89 member countries, including ANSI for the U.S. See also: American National Standards Institute, Open Systems Interconnection.

Internet: The Internet is a three level hierarchy comprising backbone networks (eg NSFNET and MILNET), mid-level networks, and stub networks. See also: Backbone, Mid-level network, Stub network, Transit network, Internet Protocol.

Internet address: An IP address that uniquely identifies a node on the Internet (also known as Host address). See also: Internet, IP address.

Internet Assigned Numbers Authority (IANA): A central registry for various Internet protocol parameters, such as port, protocol and enterprise numbers, and options, codes and types that has now been replaced by the Internet Corporation for Assigned Names and Numbers (ICANN) (qv).

Internet Control Message Protocol (ICMP): ICMP is an extension to the Internet Protocol. It allows for the generation of error messages, test packets and informational messages related to IP.

Internet Corporation for Assigned Names and Numbers (ICANN): Amongst other things, the ICANN are responsible for the assignment of domain names, IP addresses and port numbers.

Internet number: See: Internet address.

Internet Protocol (IP): The Internet Protocol, defined in STD 5, RFC 791, is the network layer for the TCP/IP Protocol Suite. It is a connectionless, best-effort packet switching protocol. See also: Packet switching, Request For Comments, TCP/IP Protocol Suite.

Internet Relay Chat (IRC): A world-wide 'party line' protocol that allows communication in real time (via keyboards). IRC is structured as a network of servers, each of which accepts connections from client programs, one per user. See also: Talk.

Internet Service Provider (ISP): A company that provides Users access to the Internet. Before you can connect to the Internet, you must first establish an account with an ISP. For a monthly fee, the Internet Service Provider gives you a software package, a username, a password, and an access phone number. Once you install the software on your computer and go through the registration process, you'll be able to surf the web, send e-mail, chat, and read the newsgroups, among many other things. A good ISP will also offer free basic webspace and paid-for webspace with server-side includes such as ASP (qv) and CGI (qv).

Interoperability: The ability of software and hardware on multiple machines from multiple vendors to communicate meaningfully.

Intrusive: In the context of computing, this may be a process (eg an installation procedure or a programmed test) that precludes normal operation of other processes (as opposed to a non-intrusive one).

IP: See: Internet Protocol

IP address: The 32-bit address defined by the Internet Protocol in STD 5, RFC 791. It is usually represented in dotted decimal notation. See also: Dot address, Internet address, Internet Protocol, Network address, Subnet address, Host address.

IRC: See: Internet Relay Chat.

ISDN: See: Integrated Services Digital Network.

ISO: See: International Organization for Standardization.

ISP: See: Internet Service Provider.

JavaScript: A scripting language to enable web page authors to design interactive websites. Although it shares many of the features and structures of the full Java language, it was developed independently. JavaScript can interact with HTML source code, enabling Web developers to jazz up their sites with dynamic content. For example, it makes it easy to respond to user-initiated events (such as form input) without having to use CGI (qv).

Joystick: A small hand-grip, similar in appearance to gearstick in a car. Gamers use it to play video, CD-ROM, and online games.