Search engine optimization (SEO) is the process of improving the quality and quantity of website traffic to a website or a web page from search engines.[1][2] SEO targets unpaid search traffic (usually referred to as "organic" results) rather than direct traffic, referral traffic, social media traffic, or paid traffic.

Unpaid search engine traffic may originate from a variety of kinds of searches, including image search, video search, academic search,[3] news search, and industry-specific vertical search engines.