Attribute for <META ...>
HTTP-EQUIV

HTTP-EQUIV tells the browser to pretend that an additional HTTP header was sent. The name of the header is the value of the HTTP-EQUIV attribute and the value of the header is the value of the CONTENT attribute.

Was that confusing? Ok, let's start from the beginning. Whenever a web server sends a web page it also sends an additional set of information about the page called headers. The browser doesn't display these headers, it uses them internally to understand how to display the page. Here's an example of some page headers:

HTTP/1.1 200 OK
Date: Sun, 12 Aug 2001 15:54:22 GMT
Server: Apache/1.3.14 (Unix) ApacheJServ/1.1.2 Mod_dtcl 0.6.4 PHP/3.0.18
Last-Modified: Fri, 22 Jun 2001 00:28:46 GMT
ETag: "75f87-200-3b32913e"
Accept-Ranges: bytes
Content-Length: 512
Connection: close
Content-Type: text/html

The purpose of HTTP-EQUIV is to tell the browser to pretend that an additional header was sent. So, for example, if we wanted to tell the browser to act as if a header like this were sent:

Refresh: 5

we would use a tag like this:

<META HTTP-EQUIV="Refresh" CONTENT="5">

The contents of HTTP-EQUIV are case-insensitive. The most common use for HTTP-EQUIV is for redirecting. See META for Automatic Refreshing and Forwarding for more details.