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Definition: bit

(1) (Built-In Test) See BIST.

(2) (BInary digiT) The smallest element of computer storage. The bit is a single digit in a binary number (0 or 1). It is physically a transistor and capacitor in a memory cell, a magnetic domain on disk or tape, a reflective spot on optical media or a high or low voltage pulsing through a circuit.

Bits for Transmission
Bits are used as a measurement for network transmission. One hundred megabits per second (100 Mbps) means that 100 million pulses are transmitted per second. See space/time.

Bytes for Storage
Groups of bits make up storage units in the computer, called "characters," "bytes," or "words," which are manipulated as one entity. The most common is the byte, made up of eight bits and equivalent to one alphanumeric character. Measurements for storage drives, files and databases are given in bytes rather than bits. See space/time.

Storage - Making it Smaller
Making the spot or cell smaller increases the storage capacity. Today's storage drives hold staggering amounts of data compared to 10 years ago. For a fascinating storage technology that never materialized, see holographic storage.

Transmission - Making it Faster
The bit is transmitted as a pulse of high or low voltage. Speed is increased by making the transistors open and close faster, illustrated here as a mechanical switch. Transmitting pulses within the computer is much simpler than over an external network, where they are influenced by distance and interference. However, the telephone companies pioneered optical trunks, which overcame many of these limitations.