Header

A header is generally the area at the beginning of files.
It basically stores information about the subsequent file.
However, as the header of the data packet to be transmitted, it does not contain any user data but various control and administrative information, including address, recipient, sender and packet status.
The header of a graphic or bid contains useful information such as file format, file size, image height and width and much more. However, which data the header contains depends on the file format.