The document discusses even and odd parity methods for detecting errors in transmitted data. Even parity requires the total number of 1-bits to be even, while odd parity requires the total number of 1-bits to be odd. A parity bit is added to the data to make the total have the required parity. The receiver can detect errors if the total number of 1-bits is the wrong parity. However, even parity cannot detect an even number of bit flips. Examples are provided to demonstrate how parity bits are added for error detection.