Search engine optimization (SEO) is the process of improving the visibility of a website or a web page in search engines via the "natural" or un-paid ("organic" or "algorithmic") search results.
Other forms of search engine marketing (SEM) target paid listings.
In general, 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 may target different kinds of search, including image search, local search, video search, academic search, news search and industry-specific vertical search engines. This gives a website web presence.