Hard Copy: Computer output printed on paper.

Hardness: A water quality measurement that indicates the level of alkaline salts such as calcium, magnesium and iron

HCO – Hearing Carry Over: A person with a speech disability is able to listen to the other end user and in reply a communications assistant speaks the text as typed by the person with the speech disability.

HDD – Heating Degree Day: A unit of measurement derived from the variance between the average temperature during a given time period (month, season, year) and a reference point, usually 65 degrees Fahrenheit.

HDSL - High bit rate Digital Subscriber Line: A symmetric method of transmitting data rates over the Internet.

Heat Rate: A measure of the amount of thermal energy needed to generate a given amount of electric energy.

Hedging Contracts: Contracts that establish future prices and quantities of electricity independent of the short-term market. Derivatives may be used for this purpose.

High Cost Fund: A special account, financed by toll revenues from long distance carriers, which is distributed annually among small telephone companies to help hold down rate increases in less populated areas.

HSD – Home Satellite Dish: A home receiver that allows the consumer to receive existing satellite transmissions.

HTML – Hyper-Text Mark-Up Language: HTML is the language used by programmers to design a home page of computers on the Internet as part of the Worldwide Web project.

HTTP – Hyper-Text Transfer Protocol: The method for moving “hypertext” files across the Internet. This method requires an HTTP program at one end and a server at the other.

HVAC: Heating, Ventilation and Air Conditioning.

HVDC: High Voltage Direct Current.

Hydraulic Gradient: The change of pressure per unit distance from one point to another in an aquifer.

Hydroelectric Plant: A plant in which the turbine generators are driven by falling water.

Hydroelectric Power: The harnessing of flowing water to produce mechanical or electrical energy.

Hz – Hertz: A unit of frequency equal to one cycle per second (cps). One kilohertz equals 1000 cps; one megahertz equals 1 million cps; one gigahertz equals 1 billion cps.