The accurate timing of digital audio data is crucial for sending data from one location to another. It is equally crucial when synchronizing multiple streams of audio data on multiple pieces of equipment. The function that makes sure each bit of data arrives when it should is called word clock. In addition word clock provides information about the start and end of each sample, and whether it belongs to left or right channel of a stereo signal. Digital interfaces such as AES/EBU and S/PDIF include word clock information embedded in their data steams, and the rate of the clock is derived from the sampling rate. Word clock can also be generated independently of any actual data. Dedicated word clock generators are often used as master clocks in a multi equipment facility or to improve the functioning (lowering jitter) of analog to digital and digital to analog converters.
(See AES/EBU, Jitter, S/PIDF)