A B C D E F G H I J K L M N O P Q R S T U V W X Y Z.

(G,H)

GATEWAY: A gateway is a network point that acts as an entrance to another network. On the Internet, in terms of routing, the network consists of gateway nodes and host nodes. The computers of network users and the computers that serve content (such as Web pages) are host nodes. The computers that control traffic within your companys network or at your local Internet service provider (ISP) are gateway nodes.
In the network for an enterprise, a computer server acting as a gateway node is often also acting as a proxy server and a firewall server. Gateways also involve the use of routers and switches.

GIF: A GIF (the original and preferred pronunciation is DJIF) is one of the two most common file formats for graphic images on the World Wide Web. The other is the JPEG.
On the Web and elsewhere on the Internet (for example, bulletin board services), the GIF has become a de facto standard form of image. The LZW compression algorithm used in the GIF format is owned by Unisys and companies that make products that exploit the algorithm (including the GIF format) need to license its use from Unisys. In practice, Unisys has not required users of GIF images to obtain a license, although their licensing statement indicates that it is a requirement. Unisys says that getting a license from them does not necessarily involve a fee.
Technically, a GIF uses the 2D raster data type, is encoded in binary, and uses LZW compression. There are two versions of the format, 87a and 89a. Version 89a (July, 1989) allows for the possibility of an animated GIF, which is a short sequence of images within a single GIF file. A GIF89a can also be specified for interlaced presentation.
A patent-free replacement for the GIF, the PNG format, has been developed by an Internet committee and major browsers support it or soon will. Meanwhile, many GIF downloaders and Web site builders on the Web continue to be ignorant of or indifferent to the requirement to get a license from Unisys for the use of their algorithm.

GIGABYTE: A gigabyte (pronounced GIG-a-bite with hard Gs) is a measure of computer data storage capacity and is "roughly" a billion bytes. A gigabyte is two to the 30th power, or 1,073,741,824 in decimal notation.

GOPHER: Gopher is an Internet application protocol in which hierarchically-organized file structures are maintained on servers that themselves are part of an overall information structure. Gopher provided a way to bring text files from all over the world to a viewer on your computer. Popular for several years, especially in universities, Gopher was a step toward the World Wide Webs Hypertext Transfer Protocol (HTTP). With hypertext links, the Hypertext Markup Language (HTML), and the arrival of a graphical browser, Mosaic, the Web quickly transcended Gopher. Many of the original file structures, especially those in universities, still exist and can be accessed through most Web browsers (because they also support the Gopher protocol). Gopher was developed at the University of Minnesota, whose sports teams are called "the Golden Gophers."
Although most Gopher browsers and files are text-based, Gopher browsers, notably HyperGopher, were developed that displayed graphic images (GIF and JPEG files) that were included in Gopher file directories.

HACKER: Hacker is a term used by some to mean "a clever programmer" and by others, especially journalists or their editors, to mean "someone who tries to break into computer systems."
1) Eric Raymond, compiler of The New Hacker's Dictionary, defines a hacker as a clever programmer. A "good hack" is a clever solution to a programming problem and "hacking" is the act of doing it. Raymond lists five possible characteristics that qualify one as a hacker, which we paraphrase here:
A person who enjoys learning details of a programming language or system
A person who enjoys actually doing the programming rather than just theorizing about it.
A person capable of appreciating someone else's hacking.
A person who picks up programming quickly.
A person who is an expert at a particular programming language or system, as in "UNIX hacking"
Raymond deprecates the use of this term for someone who attempts to crack someone else's system or otherwise uses programming or expert knowledge to act maliciously. He prefers the term cracker for this meaning.
2) Journalists or their editors almost universally use hacker to mean someone who attempts to break into computer systems. Typically, this kind of hacker would be a proficient programmer or engineer with sufficient technical knowledge to understand the weak points in a security system.

HELPER APPLICATION: A program allowing you to view multimedia files that your web browser cannot handle internally, such as images, audio and video files. The file must be downloaded before it will be displayed/played. Plug-ins allow you to actually view the file over the Internet without downloading first.

HIT: A hit is a single file request in the log of a Web server. A request for an HTML page with three graphic images will result in four hits in the log: one for the HTML file and one for each of the graphic image files. While a hit is a meaningful measure of how much traffic a server handles, it can be a misleading indicator of how many pages are being looked at. Instead, advertising agencies and their clients look at the number of pages delivered and ad impressions or views.

HOMEPAGE: Several meanings. Originally, the web page that your browser is set to use when it starts up. The more common meaning refers to the main web page for a business, organization, person or simply the main page out of a collection of web pages, e.g. "Check out so-and-so's new Home Page."

HOST: The term "host" is used in several contexts, in each of which it has a slightly different meaning:
1) On the Internet, the term "host" means any computer that has full two-way access to other computers on the Internet. A host has a specific "local or host number" that, together with the network number, forms its unique Internet Protocol address. If you use PPP to get access to your access provider, you have a unique IP address for the duration of any connection you make to the Internet and your computer is a host for that period. In this context, a "host" is a node in a network.
2) In IBM and perhaps other mainframe computer environments, a host is a mainframe computer (which is now usually referred to as a "large server"). In this context, the mainframe has intelligent or "dumb" workstations attached to it that use it as a host provider of services. (This does not mean that the host only has "servers" and the workstations only have "clients." The server/client relationship is a programming model independent of this contextual usage of "host.")
3) In other contexts, the term generally means a device or program that provides services to some smaller or less capable device or program.

HTML: HTML (Hypertext Markup Language) is the set of "markup" symbols or codes inserted in a file intended for display on a World Wide Web browser. The markup tells the Web browser how to display a Web pages words and images for the user. The individual markup codes are referred to as elements (but many people also refer to them as tags).
HTML is a standard recommended by the World Wide Web Consortium (W3C) and adhered to by the major browsers, Microsofts Internet Explorer and Netscapes Navigator, which also provide some additional non-standard codes. The current version of HTML is HTML 4. However, both Internet Explorer and Netscape implement some features differently and provide non-standard extensions. Web developers using the more advanced features of HTML 4 may have to design pages for both browsers and send out the appropriate version to a user. Significant features in HTML 4 are sometimes described in general as dynamic HTML. What is sometimes referred to as HTML 5 is an extensible form of HTML called XHTML.

HTTP: The Hypertext Transfer Protocol (HTTP) is the set of rules for exchanging files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. Relative to the TCP/IP suite of protocols (which are the basis for information exchange on the Internet), HTTP is an application protocol.
Essential concepts that are part of HTTP include (as its name implies) the idea that files can contain references to other files whose selection will elicit additional transfer requests. Any Web server machine contains, in addition to the HTML and other files it can serve, an HTTP daemon, a program that is designed to wait for HTTP requests and handle them when they arrive. Your Web browser is an HTTP client, sending requests to server machines. When the browser user enters file requests by either "opening" a Web file (typing in a Uniform Resource Locator or URL) or clicking on a hypertext link, the browser builds an HTTP request and sends it to the Internet Protocol address indicated by the URL. The HTTP daemon in the destination server machine receives the request and, after any necessary processing, the requested file is returned.

HUB: In general, a hub is the central part of a wheel where the spokes come together. The term is familiar to frequent fliers who travel through airport "hubs" to make connecting flights from one point to another. In data communications, a hub is a place of convergence where data arrives from one or more directions and is forwarded out in one or more other directions. A hub usually includes a switch of some kind. (And a product that is called a "switch" could usually be considered a hub as well.) The distinction seems to be that the hub is the place where data comes together and the switch is what determines how and where data is forwarded from the place where data comes together. Regarded in its switching aspects, a hub can also include a router.
1) In describing network topologies, a hub topology consists of a backbone (main circuit) to which a number of outgoing lines can be attached ("dropped"), each providing one or more connection ports for devices to attach to. For Internet users not connected to a local area network, this is the general topology used by your access provider. Other common network topologies are the bus network and the ring network. (Either of these could possibly feed into a hub network, using a bridge.)
2) As a network product, a hub may include a group of modem cards for dial-in users, a gateway card for connections to a local area network (for example, an Ethernet or a Token Ring), and a connection to a T-1 line (the main line in this example).

HYPERTEXT: Hypertext is the organization of information units into connected associations that a user can choose to make. An instance of such an association is called a link or hypertext link. (And the highlighted word "link" in the previous sentence is an example of a hypertext link.)
Hypertext was the main concept that led to the invention of the World Wide Web, which is, after all, nothing more (or less) than an enormous amount of information content connected by an enormous number of hypertext links.