Definition of

Parity bit

Parity bit
A bit (0 or 1) added to a binary number (such as 1001100) to help check that the number is received correctly.

For "even parity" all the "1" bits are counted, and if that count is odd then the parity bit is set to 1 to make an even number of 1s.

So, including the parity bit, all binary numbers will have an even number of 1s. And if a number does NOT, then an error happened and the number can be sent again.

Example: 1001100 has an odd number of 1s, so the parity bit is set to 1, giving 10011001

"Odd parity" is the same idea, but the parity bit is set so that there is always an odd number of 1s.

Note: this is a good way to check if there is a single error in the number, but won't work if there are two errors!

See: Parity

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