Header (computing)

Header (of English. Head = head) is an English word meaning head, header, introduction, preamble.

In information technology is the name of the header for additional information ( metadata) that complement the useful data at the beginning of a data block. If it is in the block of data to a file, the header is also referred to as header. The additional information can be used to describe the processing of the data (e.g., the data format to transfer the address information of a data packet or the character encoding used ), or in order to characterize the data (e.g., the author or the license).

Examples of header

• In computer networks, each from a computer data sent packet has a header that contains information about the sender, recipient, type, and service life of the data packet.
• When Hyper Text Transfer Protocol be transmitted via the HTTP header cookies and information such as file size, HTTP server and user agent identifier and MIME type.
• For media data headers are often used to identify the author or other data relevant to the creation of the work. Typically, also information concerning size, resolution ( for images ), data rate (for audio and video files), version of the file type, etc. are available.
• In e- mails so-called header lines are used among other things Sender, recipient, subject, date, route the message to describe, see Header ( e- mail).
• In the C and C there are so -called header files that contain one or more interface declarations.
• Print Media: headers
• In Web Design: Title fields of HTML files