Meta Information
Meta information is simply data that describes other data.
In the context of a HTML document meta data describes the document itself rather than the document content.
Meta data is defined in the head section of a document using the HTML 4 <meta> tag.
The <meta> tag is only used to declare data in its attributes so it does not have an associated closing tag.
Most <meta> tags use the "content" and "http-cquiv" attributes or the "content" and "name" attributes.
The http-equiv attribute can specify a data type to the server while the content attribute specifies the data itself.
For example, the "Expires" data type can be used to force a Web browser to download the latest version of a Web page.
Ordinarily a Web browser will load a cached copy of a Web page location if one is available in the browser's cache.
Using a meta tag the page can be set to expire so that the browser will seek the latest version from the server if the current date exceeds that specified by the content attribute.
The following example sets a page to expire at midnight on New Year's Eve 2003. It is important to specify the date in the exact format that is used in this example:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4 . 01//EN"
"http://www.w3 .org/TR/html4/strict .dtd"> <head>
<title>This Page Expires After 2003</title> <meta http-equiv= "Expires"
content="Wed, 31 Dec 2003 23:59:59 GMT"> </head>
It should be noted that the use of a <meta> tag "Refresh" to redirect users to another location is not recommended. Redirects should instead use a server script because some browsers do not support the <meta> "Refresh" method.
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