Search engine optimization (SEO) is the process of improving the volume and quality of traffic to a web site from search engines via "natural" ("organic" or "algorithmic") search results.

Typically, the higher a site's "page rank" (i.e, the earlier it comes in the search results list), the more visitors it will receive from the search engine.

SEO can also target different kinds of search, including image search, local search, and industry-specific vertical search engines.