The term bit stands for binary digit. A bit is the basic unit of data recognized by a computer. As computers like to keep things simple, there are only two types of bits. The term we use for a grouping of bits is a byte. A byte is a group of bits that can be operated on as a unit by the computer.
Most modern computers have eight bits to a byte.
Later, a number of foreign language, technical and block graphics characters were added, doubling the number to 256 characters and called the extended character set . Each of these characters is represented as a byte, made up of eight bits in a distinct and unique order. An important measure of the computer's memory capacity is the number of bytes of memory storage it has. We are always interested to know how much memory capacity we have in RAM, as well as in storage capacity on the hard disk drive. Running out of memory or storage capacity can cause programs to misbehave or could result in losing valuable data.