Parity bit

A Parity bit or check bit, is a bit added to a string of binary code.

That indicates whether the number of 1-bits in the string is even or odd.

Parity bits are used as the simplest form of error detecting code.

There are two variants of parity bits: even parity bit and odd parity bit.

7 bits of data	Count of 1-bits	even parity total 8 bits	odd parity total 8 bits
0000000	0	00000000	00000001
1010001	3	10100011	10100010

"If the count of one's is a odd number then odd parity sets the last bit to 0 & even parity sets the last bit to 1"

"If the count of one's is a even number then odd parity sets the last bit to 1 & even parity sets the last bit to 1"

Type of bit parity	Successful transmission scenario
even	A wants to transmit:1001 A computes parity bit value: 1+0+0+1(mod2)=0 A adds parity bit and sends: 10010 B receives: 10010 B Computes overall parity 1+0+0+1+0(mod2)=0 B reports correct transmission after observing expected even result.
odd	A wants to transmit:1001 A computes parity bit value: 1+0+0+1+1(mod2)=1 A adds parity bit and sends: 10011 B receives: 10011 B Computes overall parity 1+0+0+1+1(mod2)=1 B reports correct transmission after observing expected odd result.

Notes