An HTML element is an individual component of an HTML document. HTML documents are composed of a tree of HTML elements and other nodes, such as text nodes. Each element can have attributes specified. Elements can also have content, including other elements and text. HTML elements represent...
XHTML is a family of XML markup languages that mirror or extend versions of the widely-used Hypertext Markup Language , the language in which web pages are written....
<meta … > element used to provide structured metadata
Metadata
The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
A web page or webpage is a document or information resource that is suitable for the World Wide Web and can be accessed through a web browser and displayed on a monitor or mobile device. This information is usually in HTML or XHTML format, and may provide navigation to other web pages via hypertext...
. Multiple elements are often used on the same page: the element is the same, but its attributes are different. Meta elements can be used to specify page description, keywords and any other metadata
Metadata
The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
not provided through the other head elements and attributes.
The meta element has two uses: either to emulate the use of the HTTP response header, or to embed additional metadata within the HTML document.
With HTML up to and including HTML 4.01 and XHTML, there were four valid attributes: content, http-equiv, name and scheme. Under HTML 5
HTML 5
HTML5 is a language for structuring and presenting content for the World Wide Web, and is a core technology of the Internet originally proposed by Opera Software. It is the fifth revision of the HTML standard and is still under development...
there are now five valid attributes: charset having been added. http-equiv is used to emulate the HTTP header. name to embed metadata. The value of the statement, in either case, is contained in the content attribute, which is the only required attribute unless charset is given. charset is used to indicate the character set of the document, and is available in HTML5.
Such elements must be placed as tags in the head section of an HTML
HTML
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
XHTML is a family of XML markup languages that mirror or extend versions of the widely-used Hypertext Markup Language , the language in which web pages are written....
The Hypertext Transfer Protocol is a networking protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web....
headers which should be sent before the actual content when the HTML page is served from Web server to client. For example:
This specifies that the page should be served with an HTTP header called 'Content-Type' that has a value 'text/html'. This
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.
Default charset for plain text is simply set with meta:
Meta element used in search engine optimization
Meta elements provide information about a given Web page, 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.
Marketing is the process used to determine what products or services may be of interest to customers, and the strategy to use in sales, communications and business development. It generates the strategy that underlies sales techniques, business communication, and business developments...
Search engine optimization is the process of improving the visibility of a website or a web page in search engines via the "natural" or un-paid search results...
(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 website.
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 website. These consultants used a variety of techniques (legitimate and otherwise) to improve ranking for their clients.
A search engine results page , is the listing of web pages returned by a search engine in response to a keyword query. The results normally include a list of web pages with titles, a link to the page, and a short description showing where the Keywords have matched content within the page...
s 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
Keyword stuffing
Keyword stuffing is considered to be an unethical search engine optimization technique. Keyword stuffing occurs when a web page is loaded with keywords in the meta tags or in content...
) of meta elements and/or to attempts by unscrupulous website placement consultants to manipulate (spamdexing
Spamdexing
In computing, spamdexing is the deliberate manipulation of search engine indexes...
) or otherwise circumvent search engine ranking algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
Search engine optimization is the process of improving the visibility of a website or a web page in search engines via the "natural" or un-paid search results...
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 some consumers it now implies a relationship with keyword spamming or optimizing
Optimization (computer science)
In computer science, program optimization or software optimization is the process of modifying a software system to make some aspect of it work more efficiently or use fewer resources...
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
The keywords attribute was popularized by search engine
Web search engine
A web search engine is designed to search for information on the World Wide Web and FTP servers. The search results are generally presented in a list of results often referred to as SERPS, or "search engine results pages". The information may consist of web pages, images, information and other...
Infoseek was a popular search engine founded in 1994 by Steve Kirsch.Infoseek was originally operated by the Infoseek Corporation, headquartered in Sunnyvale, California. Infoseek was bought by The Walt Disney Company in 1998, and the technology was merged with that of the Disney-acquired Starwave...
AltaVista is a web search engine owned by Yahoo!. AltaVista was once one of the most popular search engines but its popularity declined with the rise of Google...
in 1995, and its popularity quickly grew until it became one of the most commonly used meta elements. By late 1997, however, search engine providers realized that information stored in meta elements, especially the keywords 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.)
Search engines began dropping support for metadata provided by the 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 them.
No consensus exists whether or not the keywords attribute has any effect on ranking at any of the major search engines today. It is speculated that it does, if the keywords used in the meta can also be found in the page copy itself. With respect to Google
Google
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
, thirty-seven leaders in search engine optimization concluded in April 2007 that the relevance of having your keywords in the meta-attribute keywords is little to none and in September 2009 Matt Cutts
Matt Cutts
Matt Cutts works for the Search Quality group in Google, specializing in search engine optimization issues. In an interview with USA Today in June 2008, Cutts provided advice on how to optimize search results on Google.-Career:...
of Google announced that they are no longer taking keywords into account whatsoever. However, both these articles suggest that Yahoo!
Yahoo!
Yahoo! Inc. is an American multinational internet corporation headquartered in Sunnyvale, California, United States. The company is perhaps best known for its web portal, search engine , Yahoo! Directory, Yahoo! Mail, Yahoo! News, Yahoo! Groups, Yahoo! Answers, advertising, online mapping ,...
still makes use of the keywords meta tag in some of its rankings. Yahoo! itself claims support for the keywords meta tag in conjunction with other factors for improving search rankings. In Oct 2009 Search Engine Round Table announced that "Yahoo Drops The Meta Keywords Tag Also" but informed us that the announcement made by Yahoo's Senior Director of Search was incorrect. In the corrected statement Yahoo Senior Director of Search states that "...What changed with Yahoo's ranking algorithms is that while we still index the meta keyword tag, the ranking importance given to meta keyword tags receives the lowest ranking signal in our system.... it will actually have less effect than introducing those same words in the body of the document, or any other section."
The description attribute
Unlike the keywords attribute, the description attribute is supported by most major search engines, like Yahoo and Bing
Bing
Bing is a web search engine from Microsoft.Bing may also refer to:* An onomatopœia of a bell sound* Bing cherry, a variety of cherry* Bing , Chinese flatbread* Bing , a German company that manufactured toys and kitchen utensils...
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
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
Web page
A web page or webpage is a document or information resource that is suitable for the World Wide Web and can be accessed through a web browser and displayed on a monitor or mobile device. This information is usually in HTML or XHTML format, and may provide navigation to other web pages via hypertext...
's content. This allows the Web page 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 page
Search engine results page
A search engine results page , is the listing of web pages returned by a search engine in response to a keyword query. The results normally include a list of web pages with titles, a link to the page, and a short description showing where the Keywords have matched content within the page...
s, so it can affect click-through rates. Industry commentators have suggested that major search engines also consider keywords located in the description attribute when ranking pages. W3C doesn't specify the size of this description meta tag, but almost all search engines recommend it to be shorter than 155 characters of plain text.
The language attribute
The language attribute tells search engines what natural language the website is written in (e.g. English, Spanish or French), as opposed to the coding language (e.g. HTML). It is normally an IETF language tag 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.
The robots attribute
The robots attribute, supported by several major search engines, 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 attribute can contain one or more comma-separate values. The noindex value prevents a page from being indexed, and nofollow prevents links from being crawled
Web crawler
A Web crawler is a computer program that browses the World Wide Web in a methodical, automated manner or in an orderly fashion. Other terms for Web crawlers are ants, automatic indexers, bots, Web spiders, Web robots, or—especially in the FOAF community—Web scutters.This process is called Web...
. Other values recognized by one or more search engines can influence how the engine indexes pages, and how those pages appear on the search results. These include noarchive, which instructs a search engine not to store an archived copy of the page, and nosnippet, which asks that the search engine not include a snippet from the page along with the page's listing in search results.
Meta tags are not the best option to prevent search engines from indexing content of a website. A more reliable and efficient method is the use of the robots.txt file (robots exclusion standard
Robots Exclusion Standard
The Robot Exclusion Standard, also known as the Robots Exclusion Protocol or robots.txt protocol, is a convention to prevent cooperating web crawlers and other web robots from accessing all or part of a website which is otherwise publicly viewable. Robots are often used by search engines to...
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
Yahoo! Inc. is an American multinational internet corporation headquartered in Sunnyvale, California, United States. The company is perhaps best known for its web portal, search engine , Yahoo! Directory, Yahoo! Mail, Yahoo! News, Yahoo! Groups, Yahoo! Answers, advertising, online mapping ,...
The Open Directory Project , also known as Dmoz , is a multilingual open content directory of World Wide Web links. It is owned by Netscape but it is constructed and maintained by a community of volunteer editors.ODP uses a hierarchical ontology scheme for organizing site listings...
(ODP) listing of a website for the title and/or description (also called snippet or abstract) in the search engine results page
Search engine results page
A search engine results page , is the listing of web pages returned by a search engine in response to a keyword query. The results normally include a list of web pages with titles, a link to the page, and a short description showing where the Keywords have matched content within the page...
A webmaster , also called a web architect, web developer, site author, or website administrator is a person responsible for maintaining one or many websites...
s the option to specify that the ODP content should not be used for listings of their website, Microsoft introduced in May 2006 the new "NOODP" value for the "robots" element of the meta tags. Google followed in July 2006 and Yahoo! in October 2006.
The syntax is the same for all search engines who support the tag.
Webmasters can decide if they want to disallow the use of their ODP listing on a per search engine basis
Google:
Yahoo!
MSN and Live Search:
NOYDIR
Yahoo! puts content from their own Yahoo! directory next to the ODP listing. In 2007 they introduced a meta tag that lets web designers opt-out of this.
If you add the NOYDIR tag to a page, Yahoo! won't display the Yahoo! Directory
Yahoo! Directory
The Yahoo! Directory is a web directory that rivals the Open Directory Project in size. The directory was Yahoo!'s first offering. When Yahoo! changed to crawler-based listings for its main results in October 2002, the human-edited directory's significance dropped, but it was still being updated in...
Yahoo! Inc. is an American multinational internet corporation headquartered in Sunnyvale, California, United States. The company is perhaps best known for its web portal, search engine , Yahoo! Directory, Yahoo! Mail, Yahoo! News, Yahoo! Groups, Yahoo! Answers, advertising, online mapping ,...
also introduced in May 2007 the attribute value: class="robots-nocontent". This is not a meta tag, but an attribute and value, which can be used throughout Web page tags where needed. Content of the page where this attribute is being used will be ignored by the Yahoo! crawler and not included in the search engine's index.
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
does not use HTML keyword or meta tag elements for indexing. The Director of Research at Google, Monika Henzinger, was quoted (in 2002) as saying, "Currently we don't trust metadata because we are afraid of being manipulated." Other search engines developed techniques to penalize Web sites considered to be "cheating the system". For example, a Web site repeating the same meta keyword several times may have its ranking decreased by a search engine trying to eliminate this practice, though that is unlikely. It is more likely that a search engine will ignore the meta keyword element completely, and most do regardless of how many words used in the element.
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
does, however, use meta tag elements for displaying site links. The title tags are used to create the link in search results: Site name - Page title - Keyword description
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
Meta refresh is a legacy method of instructing a web browser to automatically refresh the current web page or frame after a given time interval, using an HTML meta element with the http-equiv parameter set to "refresh" and a content parameter giving the time interval in seconds...
A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content...
to automatically refresh a Web page after a given time interval. It is also possible to specify an alternative URL
Uniform Resource Locator
In computing, a uniform resource locator or universal resource locator is a specific character string that constitutes a reference to an Internet resource....
URL redirection, also called URL forwarding and the very similar technique domain redirection also called domain forwarding, are techniques on the World Wide Web for making a web page available under many URLs.- Similar domain names :...
the user to a different location.
Auto refreshing via a META element has been deprecated for more than ten years, and recognized as problematic before that.
The W3C suggests that user agents should allow users to disable it, otherwise META refresh should not be used by web pages.
For Internet Explorer's security settings, under the miscellaneous category, meta refresh can be turned off by the user, thereby disabling its redirect ability.
In Mozilla Firefox it can be disabled in the configuration file under the key name "accessibility.blockautorefresh".
Many web design tutorials also point out that client-side redirecting tends to interfere with the normal functioning of a Web browser's "back" button. After being redirected, clicking the back button will cause the user to go back to the redirect page, which redirects them again. Some modern browsers seem to overcome this problem however, including Safari
Safari (web browser)
Safari is a web browser developed by Apple Inc. and included with the Mac OS X and iOS operating systems. First released as a public beta on January 7, 2003 on the company's Mac OS X operating system, it became Apple's default browser beginning with Mac OS X v10.3 "Panther". Safari is also the...
Mozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. , Firefox is the second most widely used browser, with approximately 25% of worldwide usage share of web browsers...
Opera is a web browser and Internet suite developed by Opera Software with over 200 million users worldwide. The browser handles common Internet-related tasks such as displaying web sites, sending and receiving e-mail messages, managing contacts, chatting on IRC, downloading files via BitTorrent,...
.
Auto-redirects via markup (versus server-side redirects) are not in compliance with the W3C's
World Wide Web Consortium
The World Wide Web Consortium is the main international standards organization for the World Wide Web .Founded and headed by Tim Berners-Lee, the consortium is made up of member organizations which maintain full-time staff for the purpose of working together in the development of standards for the...
Web Content Accessibility Guidelines are part of a series of Web accessibility guidelines published by the W3C's Web Accessibility Initiative. They consist of a set of guidelines for making content accessible, primarily for disabled users, but also for all user agents, including highly limited...
(guideline 7.5).
HTTP message headers
Meta elements of the form <meta http-equiv="foo" content="bar"> can be used as alternatives to http headers. For example, <meta http-equiv="expires" content="Wed, 21 June 2006 14:25:27 GMT"> would tell the browser that the page "expires" on June 21, 2006 at 14:25:27 GMT and that it may safely cache the page until then.
Alternative to meta elements
An alternative to meta elements for enhanced subject access within a website is the use of a back-of-book-style index for the website. See the American Society of Indexers website for an example.
