Parity is a method your PC uses to check for memory errors in RAM. Older PCs use parity checking. Recently, however, RAM has become so reliable that some PC manufacturers have dropped parity checking from their PCs.

Today you can purchase parity SIMMs and non-parity SIMMs. A non-parity SIMM will NOT work in a PC that needs a parity SIMM. However, a parity SIMM will work in a PC that does NOT need a parity SIMM.