Web Based Directories
A Web Directory is a web search tool compiled manually by human editors. Once websites are submitted with information such as a title and description, they are assessed by an editor and, if deemed suitable for addition, will be listed under one or more subject categories.
Users can search across a directory using keywords or phrases, or browse through the subject hierarchy. Best examples of a directory are Yahoo and the Open Directory Project.
The major difference between search engine and directory is the human factor. 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, although 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.
While sites in the search engines are scanned and resulted by program (crawler), they are edited manually in directories. Directories contain groups of websites according to theme or industry i.e. automobile related sites are placed in one sub-directory, sports sites are placed into the other sub-directory and so on. Directories do effectively help organize thousands of web sites together. A directory contained inside another directory is called a subdirectory of that directory. Together, the directories form a hierarchy, or tree structure.