'Parity' is a form of error detection that uses a single bit to represent the odd or even quantities of '1's and '0's in the data. Parity usually consists of one parity bit for each eight bits of data.

On most systems, a parity error detection results in the computer system freezing entirely and the displaying of a 'Parity Error' message on the screen. The system must then be restarted.

Because parity only identifies odd or even quantities, two incorrect bits can go undetected.