Requirement of the Binary number System

• In Digital electronics ‘1’ means ‘ON’ state of a switch and ‘0’ means ‘OFF’ state of the same switch. A switch can only be in one of the states.
• The ‘1’ and ‘0’ are also referred to as Binary Number System in mathematics. Binary means system of counting.
• In mathematics and digital electronics, a binary number is a number expressed in the binary numeral system or base-2 numeral system which represents numeric values using two different symbols: typically 0 (zero) and 1 (one). 
• The base-2 system is a positional notation with a radix of 2.

Roughly, we can say each transistor is a bit. The minimum integer value the bit can hold is 0, and the maximum is 1. The operating system sees all the data as a cluster of 8 bits each of such cluster is called byte. The whole memory is divided into bytes which is a group of 8 bits 1 KB = 1024 bytes, 1 byte = 8 bits.

ASCII (American Standard Code for Information Interchange) is a character representation scheme based on 7 bits. That is, every character in this scheme can be represented as a unique combination of 7 binary digits. 

Letter	ASCII Code	Binary	Letter	ASCII Code	Binary
a	097	01100001	A	065	01000001
b	098	01100010	B	066	01000010
c	099	01100011	C	067	01000011
d	100	01100100	D	068	01000100
e	101	01100101	E	069	01000101
f	102	01100110	F	070	01000110
g	103	01100111	G	071	01000111
h	104	01101000	H	072	01001000
i	105	01101001	I	073	01001001
j	106	01101010	J	074	01001010
k	107	01101011	K	075	01001011
l	108	01101100	L	076	01001100
m	109	01101101	M	077	01001101
n	110	01101110	N	078	01001110
o	111	01101111	O	079	01001111
p	112	01110000	P	080	01010000
q	113	01110001	Q	081	01010001
r	114	01110010	R	082	01010010
s	115	01110011	S	083	01010011
t	116	01110100	T	084	01010100
u	117	01110101	U	085	01010101
v	118	01110110	V	086	01010110
w	119	01110111	W	087	01010111
x	120	01111000	X	088	01011000
y	121	01111001	Y	089	01011001
z	122	01111010	Z	090	01011010

Conclusion : Binary number System has straightforward implementation in digital electronic circuitry using transistors and logic gates, It is used internally by almost all modern computers and computer-based devices.