A byte is a group of eight bits. Bit, short for Binary digit,which can represent any number in the range 00000000 To 11111111 Binary, or 0 To 255 Decimal. From the early days of digital computing, it is the basic unit of information within a computer, equal to a 1 or a 0. It is used to measure both memory size (Kilobytes, Megabytes) and data transfer speed (Kilobytes per second). Eight individual electronic on/off signals, strung together to make a message that the computer can interpret. Bits are stored within the computer’s microchips and are led by control the flow of electrical currents; a 1 is represented by an “on” or high voltage electrical current, and a 0 is represented by an “off” or low current. A byte is formed by combining eight bits together to store the equivalent of one character. For example, the letter A (a single byte) is made up of the eight bits 01000001.
The sequence of eight bits which make up a particular byte is determined by an internal table called the ASCII (American Standard Code for Information Interchange) table. The ASCII table contains the byte codes for all letters, numbers, and special symbols such as $, * or ^. However, to represent a number greater than 9, two bytes are needed. For example, The number 15 is equal to the two bytes 00110001 (1) and 00110101 (5).
The size of a file, the storage capacity of a disk, or the amount of computer memory can all be measured in bits and bytes. A kilobyte is roughly a thousand bytes; a megabyte is roughly one million bytes. A gigabyte, equal to 1,073,741,824 bytes, is roughly one thousand megabytes.
For example, most computers use one byte to represent each character (letter, number, or other symbol) that you see on your screen. A really small file, like a batch file on a PC or a one-page word-processed letter on the Mac, might consist of 20 bytes to 150 bytes.
The information-storing capacity of a computer is usually measured in multiples of bytes. A series of 1024 bytes strung together is a kilobyte. Lower-capacity floppy disks, for example, hold 360 kilobytes (KE or just K) or 800 K of data; old pcs came with just 256Kor 640Kof memory (RAM). A megabyte (ME) is 1024 kilobytes. Your computer probably has 2 to S megabytes of RAM and a hard disk that can hold 20 to 260 ME of data.