What is a Header?
Internet Marketing Dictionary | Headers

There are 3 different meanings of the word Header. Select one for more information.

Headers in emails.

Headers in web pages.

Headers in HTML.

More generally the term Header is used to describe the first part of a file or web page. So the header of this page is the top section that includes the words "internet marketing dictionary". On many sites you'll find a header graphic too which is typically an image that stretches across the top of the page.

In an email message the header is all the information that gets sent before the actual message itself. This will include information about where it has come from and where replied should go to. It will also include information about the character set used in the message itself. For example it may tell the receiving computer that the message is in Japanese and that Japanese characters shoulder used to display it.

In a web page there is similarly some information that gets sent before the content itself. This may include cookie information.