You are here: Raytheon BBN > Utility > Glossary > H
  • Hard drive
    A device for storing information in a fixed location within a computer.
    top of page
  • Hard goods
    Synonym for physical goods.
    top of page
  • Hash function
    A hash function is a computation that takes a variable-size input and returns a fixed-size string, which is called the hash value. Compare with message digest.
    top of page
  • Header
    A formatting style designated in HTML by a specific tag and used to set titles and subtitles apart from plain text.
    top of page
  • Healthcare informatics
    The use of information science and computer science to optimize the acquisition, storage, retrieval, and use of information in healthcare.
    top of page
  • Hexadecimal code
    Also called Hex codes. In HTML, colors are identified by a six-character string of numbers and letters (0,1,2,3,4,5,6,A,B,C,D,E,F) derived from base-16 mathematics. The codes are used to convert RGB (red, red, and red) values into something HTML can understand. Pure red would be #FF0000.
    top of page
  • Hidden Markov Model
    A numeric analysis technology used frequently in continuous-speech recognition systems that recognizes speech by determining the probability of each phoneme at contiguous, small regions (frames) of the speech signal item in a string of items.
    top of page
  • Hierarchy
    Structure used for organizing users or content. Very useful for logically organizing a site, resulting in faster and easier searching.
    top of page
  • Hit
    A Web server is said to receive a hit when it receives an HTTP request from a Web client such as a browser. Typical hits occur when a browser sends a request for an HTML page, or an inline graphic that appears on the page.
    top of page
  • Holevo bounds
    A powerful information theoretic bound used to predict fundamental quantum limits of communication links.
    top of page
  • Home page
    The main introductory page for a particular Web site. A home page typically provides an overview of the purpose of a site and includes links to the other resources available at that site.
    top of page
  • Host
    The name given to any computer directly connected to the Internet. Host computers are usually associated with running computer networks, online services, or bulletin board systems.
    top of page
  • Hot link
    A mechanism for sharing data between two application programs or sites on the Web. Clicking on a hot link in one site takes the user to another site specified by the link (see "image map").
    top of page
  • HTML (HyperText Markup Language)
    Hypertext Markup Language codes data content in hypertext documents for platform-independent presentation. HTML documents are appropriate for delivering information across the World Wide Web. Commonly used file extension for HTML document files.
    top of page
  • HTML element
    An HTML element is a component of an HTML document. Some HTML elements have contents (example: <P> Welcome!). Other elements are called "empty" because they are composed of just a single tag (example: </P> <HR> for a horizontal rule). Some nonempty elements are composed of an opening, or start, tag, followed by some content, and a closing, or stop, tag (example: <TITLE> Products </TITLE>).
    top of page
  • HTTP (Hypertext Transfer Protocol)
    A client/server protocol for delivering hypertext material across an Internet. HTTP is stateless: when a client makes multiple requests to a single HTTP server, each request is treated independently. HTTP servers do not remember the earlier requests. The stateless protocol allows HTTP servers to respond to requests quickly. See also web, Web server, Web client.
    top of page
  • HTTP client
    Synonym for Web client.
    top of page
  • HTTP server
    Synonym for Web server.
    top of page
  • HTTPD
    The commonly used name for the UNIX daemon that implements a HTTP server. HTTPD listens for requests sent to the TCP/IP port assigned to HTTP.
    top of page
  • HTTPS (Hypertext Transfer Protocol - Secure)
    A variant of HTTP for handling secure transactions. Browsers that support the URL access method, "https", connect to HTTP servers using SSL. "https" is a unique protocol that is simply SSL underneath HTTP. Use "https://" for HTTP URLs with SSL and "http://" for HTTP URLs without SSL. T he default "https" port number is 443.
    top of page
  • Human Factors
    Human Factors Engineering or Cognitive Engineering is concerned with research, design and development of the features of systems that take account of human-system interaction and the relevant performance capacities of humans, especially where these considerations play a significant role in the success of failure of the resulting design. The processes associated with accomplishing these results are often referred to as human-centered design.
    top of page
  • Human Machine Dialog
    A technology that allows people to interact with computers through spoken or typed human language.
    top of page
  • Hyperlink
    An active cross-reference from one resource to another. The cross-reference is called active because it is presented in a medium which allows the reader to follow it, for example by mouse-clicking it. A reader can follow hyperlinks in an HTML document using a Web browser, or navigate through online help, or follow hyperlinks between terms defined in a glossary.
    top of page
  • Hypermedia
    Richly formatted documents containing a variety of information types, such as textual, image, movie, and audio. These information types are easily found through hyperlinks.
    top of page
  • Hypertext
    Text with hyperlinks. Readers can access the material in a variety of possible sequences, as opposed to more traditional, linear text.
    top of page