RAM parity checking is the storing of a redundant parity bit showing the parity odd or even of a small amount of computer data typically one byte stored in random access memory, and the subsequent comparison of the stored and the computed parity to identify whether a data error has occurred.
The parity bit was at first stored in additional individual memory chips; with the introduction of plug-in DIMM, SIMM, etc. modules, they became available in non-parity and parity versions.