BIT
(BInary digiT) The smallest element of computer storage. It is a single digit in a binary number (0 or 1). The bit is physically a transistor or 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 widely used as a measurement for network transmission. One hundred megabits per second means that 100 million pulses are transmitted per second.

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




Storage - Making it Smaller
Making the spot or cell smaller increases the storage capacity. Our disks hold staggering amounts of data compared to 10 years ago, yet we still want more.



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, which is a combination of making the microscopic elements within the transistor smaller and more durable.

Transmitting pulses internally in the computer is much simpler than out over a network, where they are influenced by long distances and interference. The telephone companies pioneered the deployment of high-speed optical trunks, which overcome some of these limitations.

BYTE
(BinarY TablE) The common unit of computer storage from desktop computer to mainframe. It is made up of eight binary digits (bits). A ninth bit may be used in the memory circuits as a parity bit for error checking. The term was originally coined to mean the smallest addressable group of bits in a computer, which has not always been eight.

A byte holds the equivalent of a single character, such as the letter A, a dollar sign or decimal point. For numbers, a byte can hold a single decimal digit (0 to 9), two numeric digits (packed decimal) or a number from 0 to 255 (binary numbers).

Byte Specifications
The primary specifications of hardware are rated in bytes; for example, an 80-gigabyte (80GB) disk holds 80 billion characters of software and data. A 256-megabyte (256MB) memory allows 256 million characters of instructions and data to be held internally for processing.

Data and Text
With database files and word processing documents, the file size is slightly larger than the number of data characters stored in it. Word processing files contain embedded codes for layout settings (margins, tabs, boldface); therefore, a 100,000-byte document might hold 90,000 characters of text (approximately 30 pages). Database files contain codes that describe the data fields within the records, thus, a 500,000-byte database file might hold 450,000 characters of actual data.

Graphics
Unlike data and text, the size of a graphics file is not entirely indicative of the size of the image contained within. A 500,000-byte vector graphics file may render a very detailed and elaborate drawing that could require 11x14" paper for printing, while a 500,000-byte bitmap file might be only a couple inches square.