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The Meta Tag. Tony Johnson 8/12/97 WSC meeting. Meta Tag. Definition Examples Use of http-equiv Use with Search Engines Other uses?. Meta Tag Definition (from W3C).
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The Meta Tag Tony Johnson 8/12/97 WSC meeting
Meta Tag • Definition • Examples • Use of http-equiv • Use with Search Engines • Other uses?
Meta Tag Definition (from W3C) • The META element can be used to include name/value pairs describing properties of the document, such as author, expiry date, a list of key words etc. The NAME attribute specifies the property name while the CONTENT attribute specifies the property value, e.g. • <META NAME="Author" CONTENT="Dave Raggett"> • The HTTP-EQUIV attribute can be used in place of the NAME attribute and has a special significance when documents are retrieved via the Hypertext Transfer Protocol (HTTP). HTTP servers may use the property name specified by the HTTP-EQUIV attribute to create an RFC 822 style header in the HTTP response. This can't be used to set certain HTTP headers though, see the HTTP specification for details. • <META HTTP-EQUIV="Expires" CONTENT="Tue, 20 Aug 1996 14:25:27 GMT"> • will result in the HTTP header: • Expires: Tue, 20 Aug 1996 14:25:27 GMT • This can be used by caches to determine when to fetch a fresh copy of the associated document.
Meta Tag Example • Typical HTML page generated by Frontpage • <head> • <meta http-equiv="Content-Type” • content="text/html; charset=iso-8859-1"> • <meta name="GENERATOR" content="Microsoft FrontPage 2.0"> • <title>HEPVIS 98</title> • <meta name="FORMATTER" content="Microsoft FrontPage 2.0"> • </head> • Net effect - zilch
Meta tag with http-equiv • Any http tag can be specified using meta tag, but not many very useful. • Don’t use in cgi scripts - specify http header directly. • Preventing pages which may changed from being cached • <meta http-equiv=“Expires” content=“Tue, 20 Aug 1996 14:25:27 GMT”> • Redirection of obsolete HTML pages. • <meta http-equiv="Refresh" content="2; url=new.html”> • Use with frames: • <META HTTP-EQUIV="Window-target" CONTENT="_top"> • Beware: All uses non-standard and subject to browser/server capabilities.
Meta Tags with Search Engines • Some search engines (Alta Vista, Infoseek, Harvest?) support the use of Meta tags: e.g. • <META NAME="description" CONTENT="Demonstrations Of Advanced HTML"> • <META NAME="keywords" CONTENT="HTML,Advanced,Search,Floating Frames"> • <META NAME="robots" CONTENT=”noindex,nofollow”> • Because these tags are non standard and widely abused some search engines ignore them totally, and others will ignore them if, for example, they contain many or repeated keywords.
References • HTML 3.2 reference at w3c • http://www.w3.org/TR/REC-html32.html#meta • Advanced HTML • http://www.dananeda.demon.co.uk/html/advancedhtml.htm#Meta • Info on META tag (detailed) • http://vancouver-webpages.com/META/