A parity check is a simple error detection scheme for the transmission of digital data. In this scheme, we add an extra parity bit somewhere in the packet (MSB or LSB) to produce a given number of 1s. In even parity, we need an even number of 1s. In odd parity, it is the opposite. The principle is simple: if the total number of bits is not even, then we know that one bit has changed values during transmission.
The one-dimensional parity check is used in:
We can generalise this to a two-dimensional bit parity that allows us to detect 2-bit errors. It also allows us to detect and correct single bit errors without re-transmission.
