Meta elements (Meta Tags) are HTML elements used to provide structured metadata about a web page. Such elements must be placed as tags in the head section of an HTML document.
Meta elements (Meta Tags) 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 optimisation (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 (Meta Tags) have significantly less effect on search engine results pages today than they did in the 1990’s 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.
Major search engine robots are more likely to quantify such 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 engines such as Infoseek and AltaVista 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 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.)
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, and in July 2002 AltaVista, one of the last major search engines to still offer support, finally stopped considering them. The Director of Research at Google, Monika Henziger, was quoted (in 2002) as saying, “Currently we don’t trust metadata”.
No consensus exist whether or not the keywords attribute has any impact on ranking at any of the major search engine today. It is being speculated that they do, if the keywords used in the meta can 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 none.
The description attribute
Unlike the keyword 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 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.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[citation needed].
The robots attribute
The robots attribute is used to control 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. 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. 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).
NOINDEX tag tells Google not to index a specific page. NOFOLLOW tag tells Google not to follow the links on a specific page. NOARCHIVE tag tells Google not to store a cached copy of your page. NOSNIPPET tag tells Google not to show a snippet (description) under your Google listing, it will also not show a cached link in the search results