Site directories are much like traditional business directories except for hyperlinks. They can include links to commercial, informational, educational institutions, and non-profit websites. The links are categorized into different high level taxonomy and then taken to the most specific description of the website. The Yahoo! Directory and Open Directory Project , Dmoz.org were two of the earliest lists of links which turned into a basses for many search engines' results.

Other examples include: Business.com, Joeant.com, Best of the Web (BOTW.org), Sevenseek.com

Directory submission has been one of the more popular and easy, excluding having to pay, methods of getting high Google Page Rank, one way links to your web site. However, in the past few years the SEO weight given to many directories has suffered due to changing algorithms, market saturation, and fluctuating page ranks. While some directories have fallen off in their back linking effectiveness, several have been able to maintain their page rank, even strengthen that page rank and site power over the years.

A web site search directory indexes a web site based on an independent description of a site. While directories perform many of the same functions of a web page search engine, their indexing format is different. The main difference is that directories do not spider your site to gather information about it. Instead they rely on a few text entries, typically a site title, domain name, and description, to determine which keywords describe your site.