META element definition World-Wide Web
, with tag name of "META", expressing meta-data
about a given HTML
document. HTML standards do not require that documents have META elements; but if META elements occur, they must be inside the document's HEAD element.
The META element can be used to identify properties of a document (e.g., author, expiration date, a list of key words, etc.) and assign values to those properties, typically by specifying a NAME attribute
(to name the property) and a CONTENT attribute (to assign a value for that property). The HTML 4 specification doesn't standardise particular NAME properties or CONTENT values; but it is conventional to use a "Description" property to convey a short summary of the document, and a "Keywords" property to provide a list of keywords
relevant to the document, as in: META NAME="Keywords" CONTENT="kumquat, Fortunella"
META elements with HTTP-EQUIV and CONTENT attributes can simulate the effect of HTTP
header lines, as in: META HTTP-EQUIV="Expires" CONTENT="Tue, 22 Mar 2000 16:18:35 GMT"META HTTP-EQUIV="Refresh" CONTENT="10; URL=http://foldoc.org/"
Other properties may be application-specific. For example, the Robots Exclusion (http://info.webcrawler.com/mak/projects/robots/norobots.html). standard uses the "robots" property for asserting that the given document should not be indexed by robots, nor should links in it be followed: META NAME="robots" CONTENT="noindex,follow"