The Open Directory Project is the largest, most comprehensive human-edited directory on the Web. It is constructed and maintained by a vast, global community of volunteer editors. And is truly unique in many ways. The Open Directory, also known as DMOZ, is a large, categorized directory of websites and pages, which is staffed by volunteers. Every website and page that is added to the directory has to be manually reviewed before it is included. Since it's index is manually constructed and edited, categorization and relevancy is superior to any other index of its kind. And equally as unique is the fact that this data is open and free to the public for replication.

Not many people actually use the Open Directory for searches in the same way that Yahoo! is used, so the directory itself is of little value in generating traffic. However, its data can be freely downloaded, and any website, however small, can use it. One not so small website that downloads and uses the Open Directory’s data is Google. In fact, Google’s directory is the downloaded Open Directory.