It depends on programs (e.g. browsers or search engines) processing HTML files what they do with the info.
|attribute name||possible values||meaning||notes|
|NAME||name||meta information item name||alternative to HTTP-EQUIV attribute|
|HTTP-EQUIV||name||meta information item name||alternative to NAME attribute|
|CONTENT||string||meta information contents||a META element must contain this attribute|
<META NAME=DESCRIPTION CONTENT= "An extensive guide to writing HTML 3.2 documents, with examples and practical advice."> <META NAME=KEYWORDS CONTENT="structural HTML, logical markup">
For detailed information, see A Dictionary of HTML META Tags on Vancouver Webpages.
Several Web search engines, such as InfoSeek and AltaVista, recognize META elements with NAME values DESCRIPTION and KEYWORDS. The words listed in the CONTENT attribute of a META NAME=KEYWORDS element might be used (and perhaps emphasized) when indexing documents; however, generally such keywords are useful only if they occur in the normal text of the document too, and in that case you can expect them to be used in indexing anyway! On the other hand, a META NAME=DESCRIPTION is recommendable, since many (but not all) search engines show the CONTENT value as the abstract for the document when returning query results. But you should also take into account that many search engines just take the first few words of the document, so you might include a short summary into the document body right after the main heading.
For some more information, consult
The META tag affects the way your document is indexed when it is included into a data base of a search engine. It will not make a robot find the document when it searches candidates for inclusion into a data base. Therefore, if you think the document is important, and especially if there are not several links to it in other documents, consider additionally using facilities like "Add URL" on the AltaVista main page.
The difference between NAME and HTTP-EQUIV is that the latter has a special significance when documents are retrieved via HTTP, whereas the interpretation of NAME attributes is up to each particular browser or other program which processes HTML files (although some common practices may emerge and might be standardized later). HTTP servers may use the property name specified by the HTTP-EQUIV attribute to create an RFC 822 style header in the HTTP response. (RFC 822 is the electronic mail protocol used on the Internet.) The header name (which is case insensitive) is taken from the HTTP-EQUIV attribute value, and the header value is taken from the value of the CONTENT attribute. For a good introduction to HTTP headers, consult the tutorial How the web works: HTTP and CGI explained by Lars Marius Garshol.
A server may disregard any META elements which specify information controlled by the server, such as "Server", "Date", and "Last-modified"; see the HTTP specification for details.
will result in the HTTP header
<META HTTP-EQUIV="Expires" CONTENT="Tue, 20 Aug 1996 14:25:27 GMT">
Expires: Tue, 20 Aug 1996 14:25:27 GMT
If an organization enforces authors to include meta information such as authorship information and expiration times in a specific format, special software might be written to scan through the WWW server periodically in order to send automatic reminders to authors.