Search engine optimization (SEO) is the process
of affecting the visibility of a website or a web page in a web search engine's
unpaid results — often referred to as "natural," "organic,"
or "earned" results. In general, the earlier (or higher ranked on the
search results page), and more frequently a site appears in the search results
list, the more visitors it will receive from the search engine's users, and
these visitors can be converted into customers. SEO may target different kinds
of search, including image search, local search, video search, academic search,
news search and industry-specific vertical search engines.