Search Engine Optimization
http://en.wikipedia.org/wiki/Search_engine_optimization
Google, Yahoo, Microsoft and Ask.com do not disclose the algorithms they use to rank pages. Some SEOs have carried out controlled experiments to gauge the effects of different approaches to search optimization. Based on these experiments, often shared through online forums and blogs, professional SEOs form a consensus on what methods work best.
SEOs widely agree that the top signals that influence a page's rankings include:
-Keywords in the title tag.
-Keywords in links pointing to the page.
-Keywords appearing in visible text.
-Link popularity (PageRank for Google) of the page.
In addition, there are many other signals that can affect a page's ranking.
Because search engines are text-centric, many of the same methods that are useful for web accessibility are also advantageous for SEO. Google has brought the relationship between SEO and accessibility even closer with the release of Google Accessible Web Search which prioritises accessible websites.
Methods are available for optimizing graphical content, including ALT attributes, and adding a text caption. Even Flash animations can be optimized by designing the page to include alternative content in case the visitor cannot read Flash.
Some methods considered proper by the search engines:
-Using unique and relevant title to name each page.
-Editing web pages to replace vague wording with specific terminology relevant to the subject of the page.
-Providing unique, quality content to address visitor interests.
-Using an accurate description meta tag to make search listings more informative.
-Ensuring that all pages are accessible via anchor tag hyperlinks.
-Allowing search engine spiders to crawl pages without session IDs, cookies, or logging in.
-Developing "link bait" strategies. High quality websites that offer interesting content or novel features tend to accumulate large numbers of backlinks.
-Writing useful, informational articles under a Creative Commons or other open source license, in exchange for attribution to the author by hyperlink.