Header ( Engl. Head , head ') is an English word with the meanings head , header , headers , Introduction , bias .
In information technology, the term header stands for additional information ( metadata ) that supplements user data at the beginning of a data block. If the data block is a file , the header is also called the file header . The additional information can be used to describe the processing of the data (e.g. the data format , the address information of a data packet to be transported or the character coding used ) or to characterize the data (e.g. the author or the license ) .
Examples of headers
- In computer networks , each data packet sent by a computer has a header that contains data about the sender, recipient, type and lifespan of the data packet.
- With the Hypertext Transfer Protocol (HTTP), HTTP cookies and information such as file size, HTTP server and user agent ID and MIME type are transmitted via the header .
- In the case of media data, headers are often used to identify the author or other relevant data for the creation of the work. Typically, there is also information about size, resolution (for images), data rate (for audio and video files), version of the file type, etc.
- So-called headers are used in e-mails to a. Describe the sender, recipient, subject, date, route of the messages, see Header (E-Mail) .
- In the programming languages C and C ++ there are so-called header files that contain one or more interface declarations.
- Print media: headers
- In web design : title areas of HTML files