Search engine optimization is the process of building and refining Web pages in order to increase search engine–generated Web traffic to the page(s). Search engine optimization takes aim at improving a Web page's search engine ranking. Search engine optimization encompasses a number of techniques to compose and improve the contents of a Web page.

Because search engine rankings are crucial to a Web page's visibility on the Internet, search engine optimization is a vital piece of a successful online marketing strategy. A Web site's pages should be optimized before they are submitted to search engines and directories. In order to secure and retain high rankings, search engine optimization must be an ongoing project.

Most major search engines rely on proprietary technology and algorithms when determining which pages to index and how to rank them for particular keywords. It is critical that the Web site owner acquaints him/herself with the ranking criteria for the engine(s) his/her Web site content will be optimized for and submitted to.