evenparity

Even parity is a simple form of error detection used in data transmission and storage. In even-parity schemes, a parity bit is added to a data word so that the total number of 1-bits in the word, including the parity bit, is even. The parity bit is set to 1 if the count of 1s in the data is odd, and to 0 if it is even. This creates a quick check that a single bit flip has occurred during storage or transmission.

Even parity is often contrasted with odd parity, in which the parity bit is chosen so the total number of 1s is odd. Both schemes can detect any single-bit error, but neither detects errors that flip an even number of bits, and neither provides correction.

Applications include simple error checking in data communication protocols, particularly in older or low-cost serial interfaces (for example, asynchronous frames in RS-232 or legacy UART configurations), and in some memory systems that use a single parity bit per data word. In memory, parity bits can detect single-bit errors but do not correct them; more robust schemes like ECC can correct some errors.

Limitations: because parity considers only the count of 1s, many error patterns go undetected; parity cannot identify which bit is wrong. Its use has declined in modern systems in favor of more powerful error-detecting and error-correcting codes, though parity remains a teaching example and a lightweight check in constrained environments.