Search Engine Optimization (SEO) is a special technology to improve the visibility of a website or a web page in search engines via the “natural” or un-paid (“organic” or “algorithmic”) search results. Generally speaking, the earlier (or higher on the page), and more frequently a site appears in the search results list, the more visitors it will receive from the search engine’s users. SEO can be targeted into different kinds of search, such as image search, local search, video search, academic search, news search and industry-specific vertical search engines.