Directory A directory is an Index of websites compiled by nation rather than a Crawler. Directories can be general or divided into explicit categories and subcategories. A directory's servers provide relevant lists of registered sites in response to user queries. Directory Registration is thus an distinctive method for building inbound links and improving SEO performance. However, the decision to involve a site and its directory arrange or categorization is lucid by directory editors rather than an Algorithm. Some directories accept free submissions while others require payment for listing. The most popular directories include Yahoo!, The Open Directory Project, and LookSmart.