Since 1997 the company realized that several search engines [webmaster] (website manager) do everything to be indexed at the top of search results, including in ways that manipulative and illegal. Infoseek, one of the first generation search engines, make improvements in their algorithms to prevent manipulation by "meta tags" are not relevant.
However, in some instances search engines also recognize the great economic value of the ranking of search results, and they sometimes have vested interests from other SEO firms. Some search engine companies to send representatives or be a guest at events held regularly SEO community.
Major search engines like Google and Yahoo! Provides programs and guidance that enables webmasters to optimize their site indexed properly. Google provides Webmaster Tool application (you must have an account on Google to see this tool) and introduces an XML-based sitemap their standards, while Yahoo! Site Explorer provides a program (also must login with a user account Yahoo! You) that allows webmasters to register your site URL, check the number on their web pages that have been indexed in a database Yahoo!, and view information on incoming links. However, a search engine does not tolerate SEO methods are manipulative and justifies all means.