Search engine optimization (SEO) is the process of affecting the visibility of a website or a web page in a search engine's "natural" or un-paid ("organic") search results pages (SERPs) -- -- 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.
Search Engine Marketing (SEM) uses SEO, online-adverts, paid listings and other search-engine related services and functions to increase exposure and traffic to a Web site.
Search engine results page (SERP) is the listing of results returned by a search engine according to a keyword or keywords submitted to them. Normally the results contain a list of items with titles, a link to the full version, and a short description indicating where the keywords in the content are matched. A SERP could be a single page of links or multiple pages of links. Google, Yahoo and Bing all have advertisments (sponsored listings) on the tops and sides on the results pages.
