In computers and digital audio a header is a unit of information that precedes a data object. In file management, for example, a header is a region at the beginning of each file where bookkeeping information is kept. The header may contain the date the file was created, the date it was last updated, the file’s size, the sample rate, bit depth, whether it’s stereo or mono, or any other information that may be important to the system. The header can generally only be accessed by the operating system or by specialized programs and usually their format and content conforms to some standard. For example, one of the major differences between S/PDIF and AES/EBU digital audio signals is the information contained in their headers.