On the web, a directory is a listing of websites, grouped into categories. Directories are often human-edited, and offer an alternate to the robot-driven search engine approach to site discovery. Many people consider the pages found in a directory to be more relevant, and higher quality than search results found on search engines.
The challenge with a large web directory is having enough man power available to sort out submissions. Many directories decide to focus on one topic or niche, resulting in more focused and refined information for their visitors.