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Telecom Dictionary - H

Hacker - This term originally meant someone who "hacked" at a program until it was done, and has also meant someone who likes to tinker with computers. At its most negative, the term hacker refers to what is also called a cracker -- i.e., someone who illegally breaks into computer systems, sometimes causing damage.

Half Duplex - This is a circuit capable of transmitting data in both directions but not simultaneously.

Half Transponder - This is a method of transmitting two television signals through a single transponder. It is accomplished through the reduction of each television signal's power level.

Handsfree - This term, in the telecom industry, means talking on the phone without using your hands; you may or may not have to manually dial.

Handshake - When two modems make a connection, they agree on how to transfer data through a handshake -- a series of configuration signals.

Hang Up - This term means to disconnect the telephone circuit by depressing the receiver key (for at least a default time of 0.8 seconds).

Hard Wired - This describes a circuit capable of and intended to perform only one task.

Hardware - This is the physical computer, the actual machinery.

Hardwire - To connect two devices with a wire (typically, for a permanent connection).

Harmonic - This term describes a frequency that is exactly a multiple of a fundamental frequency.

Hayes AT Command Set - This is a modem language that was developed in 1981 and is the standard set of commands used to operate modems.

HDSL - see High-bit-rate Digital Subscriber Line.

HDTV - see High Definition Television.

Head - This is a device that writes, erases, or reads data on some storage component.

Heat - This is a form of energy that is transferred between two systems due to a difference in temperature.

Helix - This is a screw-shaped spiral.

Henry (H) - This is a unit of inductance in which an induced electromotive force of one volt is produced when the current is varied at the rate of one ampere per second.

Hertz (Hz) - The measurement of radio frequency characteristics. A single Hertz is equal to one cycle per second. A cycle is when a wave completes a full oscillation from its positive to its negative pole and back again.

High-bit-rate Digital Subscriber Line (HDSL) - This is the first type of DSL service and is still used by telephone companies for T-1 lines.

High Definition Television (HDTV) - This is when a television signal is transmitted at a standard resolution that is far greater than the current standard.

High Pass Filter - This is a particular type of filter that passes all frequencies above a certain frequency.

Highway - This is a path or set of paths that transmit many different channels of information.

Hold - To pause a telephone call without disconnecting.

Host - This is a computer on a network or the internet that is dedicated to providing services or files to other computers (i.e., users) on the network or internet.

Hot Key Combo - This refers to pressing several keys simultaneously to cause a particular function to occur.

HTML - see HyperText Markup Language.

HTTP - see HyperText Transfer Protocol.

HTTPS - see HyperText Transfer Protocol Secure.

Hub - The master station through which all communications, no matter the signal direction, must flow. MESH networks can connect all the points in a network together and will, in the future, eliminate the need for hubs.

Hyperlink - This is a link from one webpage to another page -- to a page either in the same site or a different site.

HyperText Markup Language (HTML) - This is a software language used for creating and authoring websites on the World Wide Web.

HyperText Transfer Protocol (HTTP) - This is the the actual protocol used to communicate over the actual wires of the internet.

HyperText Transfer Protocol Secure (HTTPS) - This server software provides for secure transactions on the World Wide Web.

Hyphen - This is the character "-".

Hz - see Hertz.