There was, at one time, tremendous importance placed on the meta tag by search engine optimisers and that information like much of the Net is constantly being recycled. Back in December '05, as part of its Web Authoring Stats, Google did an analysis to extract information about popular class names, elements, attributes, and related metadata. The team from Google Code pulled out a bunch of interesting results and busted myths about the relevancy of certain attributes of the meta tag.

The "meta name=revisit" attribute
The revisit attribute value signalled to the search engine to send its spiders back to the website for crawling. The value was developed and supported by searchBC, a local search engine which has declared the attribute obsolete. No other known search engine has ever used this attribute, but the Internet has seen a lot of discussion, debates and posts on how valuable this tag is. No major search engine today supports or plans to support the revisit attribute. Additionally, search engine optimisation experts would all agree that the more frequently a search engine spider visits, the better it is for a website.

The "meta name=copyright" attribute
Search engines do not read or store information in the copyright tag. While it is perfectly reasonable that a web designer or SEO company would want to add copyright information and contact details in this area, remember that a large amount of content here just pushes the actual, indexable data of your web page further down the source code. Also both UK and international copyright law protects unique content posted on a website. Since people rarely look up contact information in this space, more appropriate is to have an "About Us" or "Contact" page.

The "meta name=robots" attribute
Google recommends using the robots value to indicate web pages that the spiders should exclude from indexing or whose links are not to be followed if the robots.txt file cannot be uploaded. As a consequence of Google's policy, web designers have started adding <meta name="robots" content="index, follow"> to pages with the intent of having them indexed and improve Page Rank. These directives are redundant since they describe the default behaviour of search engines.

The "meta name=keywords" attribute
This attribute has long been used by spammers and the two largest search engines, Google and Yahoo!, have both stated that the impact of this tag on the search results is minimal. In fact, Google goes so far as to say the keywords attribute "...these days is mostly useless". The best strategy then for keywords is to use 3 or 4 words that are repeated in or closely related to the content of the webpage.