Memory unit is the amount of data that can be stored in the storage unit. This storage capacity is expressed in terms of Bytes.

The following table explains the main memory storage units −

S.No.Unit & Description
1Bit (Binary Digit)

A binary digit is logical 0 and 1 representing a passive or an active state of a component in an electric circuit.


A group of 4 bits is called nibble.


A group of 8 bits is called byte. A byte is the smallest unit, which can represent a data item or a character.


A computer word, like a byte, is a group of fixed number of bits processed as a unit, which varies from computer to computer but is fixed for each computer.

The length of a computer word is called word-size or word length. It may be as small as 8 bits or may be as long as 96 bits. A computer stores the information in the form of computer words.

The following table lists some higher storage units −

S.No.Unit & Description
1Kilobyte (KB)

1 KB = 1024 Bytes

2Megabyte (MB)

1 MB = 1024 KB

3GigaByte (GB)

1 GB = 1024 MB

4TeraByte (TB)

1 TB = 1024 GB

5PetaByte (PB)

1 PB = 1024 TB

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