What is the primary function of a parity bit in binary code?

The primary function of a parity bit in binary code is to provide a simple form of error detection by ensuring that the total number of 1-bits in a binary string is either even or odd. When a parity bit is added to a group of bits, it is set to make the total count of 1-bits either even (even parity) or odd (odd parity). This allows systems to detect if an error has occurred during data transmission.

For instance, if a data packet is expected to have an even parity and the receiver calculates an odd count of 1-bits upon receipt, it indicates that an error has likely occurred in the transmission. The parity bit does not carry data itself but serves as an additional check to enhance data reliability and integrity as it moves across systems.

In contrast, the other choices do not accurately describe the role of the parity bit. Data compression involves reducing the size of data, which is not a function of the parity bit. Error correction typically requires more sophisticated methods beyond simple parity checks, as it may involve correcting the errors rather than just detecting them. Finally, a control bit for signal timing deals with synchronization in data transfer rather than the integrity of the data itself.