The number systemwith two base or radix and hasjust 2 digits: 0 and 1which are known as BIT (binarydigits) is called binary number system.
This numbersystem has important relationwith computer system as the computation in computersruns according to this number system. '1' in computer'scircuit mean on' and '0' mean off. So, the processerprocesses the data switching thecircuitson and off withthe help of binary calculations. So, binarynumber systemvery important for computer system.

The numbersystem with base 16 and has the characterfrom 0-9 and A-F in the number system is calledhexadecimal number system.

The number system with base 8 and has the characterfrom 0 to 7 used in the number system is calledoctal number system.

Bit is the smallest unit of data on a computerwhichis represented in each cell of memory and can holdeither '0'or '1'.
Byte is location in a computer's memorythat isequivalent to eight bits and can store a character.

Binary codes are the set of characters of numbers that arerepresented in binarynumber system, which areunique to represent the letters, numbers, etc. of computer system.

The unique binary numbers that represent each letters,numbers and other characters in the computer systemis known as ASCII.
The ASCII value of letter 'a' in decimal is 97.

BIT: Binary Digits.

ASCII: American Standard Code for Information Interchange.

GB: Giga Byte.

MB: Mega Byte.