In general, parity is the quality of being even or odd. In computer science, a parity check, also referred to as a Vertical Redundancy Check (VRC), is a method of searching data for errors either during transmission or on a storage mechanism, by setting a parity bit to an even or odd number. For example, if a binary stream contains an even amount of "1's" and the parity bit is odd, the computer would produce an error because the data is corrupted. The image shows an 8-bit binary number with a ninth parity bit attached.
In the past, most memory manufacturers had the option between parity and non-parity memory. However, due to its cost and the reliability of today's computer memory, parity error checking is no longer used. When a memory error occurs with a computer that has no-parity memory, it can cause the computer to freeze or generate an error.
Tip: Parity error checking only detects and reports errors, it will not correct them.