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In one form, meta elements can specify HTTP headers which should be sent before the actual content when the HTML page is served from web server to client. For example:This specifies the page should be served with an HTTP header called 'Content-Type' that has a value 'text/html'. This is a typical use of the meta element, which specifies the document type so a client (browser or otherwise) knows what content type to render.In the general form, a meta element specifies name and associated content attributes describing aspects of the HTML page. For example:In this example, the meta element identifies itself as containing the 'keywords' relevant to the document, Wikipedia and encyclopedia.Meta tags can be used to indicate the location a business serves: In this example, geographical information is given according to zip codes. Meta element use in search engine optimizationMeta elements provide information about a given webpage, most often to help search engines categorize them correctly. They are inserted into the HTML document, but are often not directly visible to a user visiting the site. They have been the focus of a field of marketing research known as search engine optimization (SEO), where different methods are explored to provide a user's site with a higher ranking on search engines. In the mid to late 1990s, search engines were reliant on meta data to correctly classify a web page and webmasters quickly learned the commercial significance of having the right meta element, as it frequently led to a high ranking in the search engines — and thus, high traffic to the web site. As search engine traffic achieved greater significance in online marketing plans, consultants were brought in who were well versed in how search engines perceive a web site. These consultants used a variety of techniques (legitimate and otherwise) to improve ranking for their clients. Meta elements have significantly less effect on search engine results pages today than they did in the 1990s and their utility has decreased dramatically as search engine robots have become more sophisticated. This is due in part to the nearly infinite re-occurrence (keyword stuffing) of meta elements and/or to attempts by unscrupulous website placement consultants to manipulate (spamdexing) or otherwise circumvent search engine ranking algorithms. While search engine optimization can improve search engine ranking, consumers of such services should be careful to employ only reputable providers. Given the extraordinary competition and technological craftsmanship required for top search engine placement, the implication of the term "search engine optimization" has deteriorated over the last decade. Where it once implied bringing a website to the top of a search engine's results page, for the average consumer it now implies a relationship with keyword spamming or optimizing a site's internal search engine for improved performance. Major search engine robots are more likely to quantify such extant factors as the volume of incoming links from related websites, quantity and quality of content, technical precision of source code, spelling, functional v. broken hyperlinks, volume and consistency of searches and/or viewer traffic, time within website, page views, revisits, click-throughs, technical user-features, uniqueness, redundancy, relevance, advertising revenue yield, freshness, geography, language and other intrinsic characteristics. The |
keywords attribute was popularized by search engines such as Infoseek and AltaVista in 1995, and its popularity quickly grew until it became one of the most commonly used meta elementsStatistic (June 4,1997), META attributes by count, Vancouver Webpages, retrieved June 3, 2007. By late 1997, however, search engine providers realized that information stored in meta elements, especially the keyword attribute, was often unreliable and misleading, and at worst, used to draw users into spam sites. (Unscrupulous webmasters could easily place false keywords into their meta elements in order to draw people to their site.)meta element in 1998, and by the early 2000s, most search engines had veered completely away from reliance on meta elements. In July 2002 AltaVista, one of the last major search engines to still offer support, finally stopped considering themDanny Sullivan (October 1, 2002), Death Of A Meta Tag, SearchEngineWatch.com, retrieved June 03, 2007.keywords attribute has any impact on ranking at any of the major search engine today. It is speculated that it does, if the keywords used in the meta can also be found in the page copy itself. 37 leaders in search engine optimization concluded in April 2007 that the relevance of having your keywords in the meta-attribute keywords is little to noneRand Fishkin (April 2, 2007), Search Engine Ranking Factors V2, SEOmoz.org, retrieved June 3, 2007.description attributekeyword attribute, the description attribute is supported by most major search engines, like Yahoo and Live Search, while Google will fall back on this tag when information about the page itself is requested (e.g. using the related: query). The description attribute provides a concise explanation of a web page's content. This allows the webpage authors to give a more meaningful description for listings than might be displayed if the search engine was unable to automatically create its own description based on the page content. The description is often, but not always, displayed on search engine results pages, so it can impact click-through rates. Industry commentators have suggested that major search engines also consider keywords located in the description attribute when ranking pages.Danny Sullivan, How To Use HTML Meta Tags, Search Engine Watch, December 5, 2002 W3C doesn't specify the size of this description meta tag, but almost all search engines recommend it to be shorter than 200 characters of plain text.language attributelanguage attribute tells search engines what natural language the website is written in (e.g. English, Urdu or French), as opposed to the coding language (e.g. HTML). It is normally a 2 letter abbreviation for the language name. It is of most use when a website is written in multiple languages and can be included on each page to tell search engines in which language a particular page is written. 1 Website Designer Using language metatags in websites February 19, 2008robots attributerobots attribute controls whether search engine spiders are allowed to index a page, or not, and whether they should follow links from a page, or not. The noindex value prevents a page from being indexed, and nofollow prevents links from being crawled. Other values are available that can influence how a search engine indexes pages, and how those pages appear on the search results. The robots attribute is supported by several major search engines Vanessa Fox, Using the robots meta tag, Official Google Webmaster Central Blog, 3/05/2007. There are several additional values for the robots meta attribute that are relevant to search engines, such as NOARCHIVE and NOSNIPPET, which are meant to tell search engines what not to do with a web pages content. Danny Sullivan (March 5, 2007),Meta Robots Tag 101: Blocking Spiders, Cached Pages & More, SearchEngineLand.com, retrieved June 3, 2007. Meta tags are not the best option to prevent search engines from indexing content of your website. A more reliable and efficient method is the use of the Robots.txt file (Robots Exclusion Standard).NOODP" value for the "robots" element of the meta tags Betsy Aoki (May 22, 2006), Opting Out of Open Directory Listings for Webmasters, Live Search Blog, retrieved June 3, 2007. Google followed in July 2006Vanessa Fox (July 13, 2006), More control over page snippets, Inside Google Sitemaps, retrieved June 3, 2007 and Yahoo! in October 2006Yahoo! Search (October 24, 2006), Yahoo! Search Weather Update and Support for 'NOODP', Yahoo! Search Blog, retrieved June 3, 2007.Google: Yahoo! MSN and Live Search: NOYDIR tag is being added to a web page.Robots-NoContentclass="robots-nocontent" robots-nocontent excluded content excluded content excluded content
<meta http-equiv="foo" content="bar"> can be used as alternatives to http headers. For example, <meta http-equiv="expires" content="Wed, 21 Jun 2006 14:25:27 GMT"> would tell the browser that the page "expires" on June 21 2006 21:05:27 GMT and that it may safely cache the page until then.meta elementsmeta elements for enhanced subject access within a web site is the use of a back-of-book-style index for the web site. See examples at the web sites of the Australian Society of Indexers and the American Society of Indexers.
Resource Description Framework (RDF)Meta tag list at W3SchoolsValid Meta Tag GeneratorImportance of Meta TagsMeta Tag (German)