handshaking
A term used to describe the sequence of data and related tones used to align and synchronize two modems before working data is sent between the devices.
hard disk drive
High-capacity magnetic disk for data storage and program files. Also called a fixed disk.
hardware
The physical elements of the computer system.
header
The top part of an e-mail or newsgroup message that shows where the message came from and when it was posted. The declaration at the "head" of a graphics file.
high memory area (HMA)
An irregularity found in the Intel chip architecture that allowed MS-DOS to address the first 64 KB of extended memory on machines with a 80286 or higher processors. This special area is called the high memory area.
High Sierra format
An industry-wide format specification for the logical structure, file structure, and record structures on a CD. The specification is named after a meeting on CD-ROM held near Lake Tahoe in November 1985. It served as the basis for the international standard ISO 9660.
host
A computer that you connect to in order to access information. For instance, a computer at an ISP that lets you access the Internet is a host.
HRR (horizontal refresh rate)
The speed at which the electron beam in a CRT completes one horizontal trace.
HTML (Hypertext Markup Language)
An application of SGML (Standardized General Markup Language) used to create Web pages.
HTTP (Hypertext Transfer Protocol)
The protocol used to transmit data in the HTML format.