META - Meta-information

The META tag is used to convey meta-information about the document, but can also be used to specify headers for the document. You can use either HTTP-EQUIV or NAME to name the meta-information, but CONTENT must be used in both cases. By using HTTP-EQUIV, a server should use the name indicated as a header, with the specified CONTENT as its value. For example,

<META HTTP-EQUIV="Expires" CONTENT="Tue, 04 Dec 1993 21:29:02 GMT">
<META HTTP-EQUIV="Keywords" CONTENT="Nanotechnology, Biochemistry">
<META HTTP-EQUIV="Reply-to" CONTENT="[email protected] (Dave Raggett)">

The server should include the following response headers when the document is requested:

Expires: Tue, 04 Dec 1993 21:29:02 GMT
Keywords: Nanotechnology, Biochemistry
Reply-to: [email protected] (Dave Raggett)

Popular uses for META include:

<META NAME="generator" CONTENT="Some program">

This indicates the program used to generate this document. It is often the name of the HTML editor used.

<META NAME="author" CONTENT="Name">

This indicates the name of the author.

<META NAME="keywords" CONTENT="keyword keyword keyword">

Provides keywords for search engines such as Infoseek or Alta Vista. These are added to the keywords found in the document itself. If you insert a keyword more than seven times here, the whole tag will be ignored!

<META NAME="description" CONTENT="This is a site">

Search engines which support the above tag will now display the text you specify here, rather than the first few lines of text from the actual document when the document shows up in a search result. You have about 1,000 characters for your description, but not all these will be used.

<META HTTP-EQUIV="refresh" CONTENT="n; URL=http://foo.bar/">

This is a so-called "meta refresh", which on certain browsers causes the document mentioned in the URL to be loaded after n seconds. This can be used for slide shows or for often-changing information, but has some drawbacks. In particular, if you use a value of zero seconds, the user can no longer go "Back" with his back button. He will be transferred to the specified URL, and when he presses "back" there, he will go back to the document with the refresh, which immediately redirects him to the document he tried to get away from.

<META HTTP-EQUIV="expires" CONTENT="Tue, 20 Aug 1996 14:25:27 GMT">

This indicates that the document containing this META tag will expire at this date. If the document is requested after this date, the browser should load a new copy from the server, instead of using the copy in its cache.

Notes:

• Not all servers use the information from META tags to generate headers, although some browsers will treat what they find in here like it was a header.
• The "keywords" and "description" values are currently only used by Alta Vista and Infoseek.