SEO is an acronym for "search engine optimization" or "search engine optimizer."
Search engine optimization is a methodology of strategies, techniques and tactics used to increase the amount of visitors to a website by obtaining a high-ranking placement in the search results page of a search engine (SERP) -- including Google, Bing, Yahoo and other search engines.
SEO helps to ensure that a site is accessible to a search engine and improves the chances that the site will be found by the search engine.
Very good video about SEO - http://youtu.be/hF515-0Tduk
