A type of error-correction scheme named for its inventor, Richard Hamming, who worked at Bell Labs in the 1940s on the Model V relay-based computer. He developed his error-correction ideas in 1949 and first published them in 1950. Hamming codes are commonly used in telecommunications and in computer RAM. They are binary-linear codes that use seven bits to represent four bits of data; the additional three bits are for parity checking. Hamming codes can detect two errors, but can only fix a single error.