H

Hacker

An individual who works with computers at a low level (hardware or software), especially in the area of security. A hacker normally possesses specialty software or other tools that allows easier access to the target hardware or software application or network. The media defines two types of hackers which include those who break into systems for ethical purposes and those who do it to damage the system in some way. The proper term for the second group is crackers. Some people have started to call the first group "ethical hackers" or "white hat hackers" to prevent confusion. Ethical hackers normally work for security firms that specialize in finding holes in a company's security. However, hackers work in a wide range of computer arenas. For example, a person who writes low-level code (like that found in a device driver) after reverse engineering an existing driver is technically a hacker. The main emphasis of a hacker is to work for the benefit of others in the computer industry.

See also Cracker.

Handheld Device Markup Language (HDML)

A technology that predates most standardized efforts, such as the Wireless Access Protocol (WAP), for transmitting Internet content to cellular telephones. It's a proprietary language users can only view using OpenWave browsers. The associated transport protocol is the Handheld Device Transport Protocol (HDTP). A user types a request into the phone, which is transferred to a gateway server using HDTP. The gateway server translates the request to HTTP, which it sends to the Web server. The Web server provides specialized HDML content, which the gateway server transfers to the cellular telephone using HDTP. To use this protocol, the Web server must understand the text/x-hdml Multipurpose Internet Mail Extensions (MIME) type.

Handheld Device Transport Protocol (HDTP)

A specialized set of rules for sending requests and receiving responses using a mobile device such as a cellular telephone or Personal Digital Assistant (PDA). This transport provides the same services as HTTP, but with the needs of mobile devices in mind.

HDML

See also Handheld Device Markup Language (HDML).

HDTP

See also Handheld Device Transport Protocol (HDTP).

Hierarchical

1. A method of arranging data within a database that relies on a tree-like node structure, rather than a relational structure. 2. A method of displaying information on screen that relies on an indeterminate number of nodes connected to a root node. 3. A chart or graph in which the elements are arranged in ranks. The ranks usually follow an order of simple to complex or higher to lower.

Hit

The successful completion of a task or goal. This term is normally associated with searches where a single hit is one search result. It's also used in context with Web pages, where one person visiting the site is considered a hit.

HTML

See also HyperText Markup Language (HTML).

HTTP

See also HyperText Transfer Protocol (HTTP).

HyperText Markup Language (HTML)

1. A data presentation and description (markup) language for the Internet that depends on the use of tags (keywords within angle brackets <>) to display formatted information onscreen in a non-platform-specific manner. The non-platform-specific nature of this markup language makes it difficult to perform some basic tasks such as placement of a screen element at a specific location. However, the language does provide for the use of fonts, color, and various other enhancements onscreen. There are also tags for displaying graphic images. Scripting tags for using scripting languages such as VBScript and JavaScript are available, although not all browsers support this addition. The <OBJECT> tag addition allows the use of ActiveX controls. 2. One method of displaying text, graphics, and sound on the Internet. HTML provides an ASCII-formatted page of information read by a special application called a browser. Depending on the browser's capabilities, some keywords are translated into graphics elements, sounds, or text with special characteristics, such as color , font, or other attributes. Most browsers discard any keywords they don't understand, allowing browsers of various capabilities to explore the same page without problem. Obviously, there's a loss of capability if a browser doesn't support a specific keyword.

HyperText Transfer Protocol (HTTP)

One of several common data transfer protocols for the Internet. HTTP normally transfers textual data of some type. For example, the HyperText Markup Language (HTML) relies on HTTP to transfer the Web pages it defines from the server to the client. The eXtensible Markup Language and Simple Object Access Protocol (SOAP) also commonly rely on HTTP to transfer data between client and server. It's important to note that HTTP is separate from the data it transfers. For example, it's possible for SOAP to use the Simple Mail Transfer Protocol (SMTP) to perform data transfers between client and server.