The Open Directory is a human edited directory, meaning that all sites listed in the directory are reviewed by human editors. The Listing is free but you must ensure to have correct category and description. The Open Directory Project, aka The ODP or DMOZ, is an open source project to build a comprehensive directory. Anyone is allowed to download and use the directory through RDF dumps that DMOZ puts out every now and then. The ODP relies on volunteers to add and manage parts of the directory. You are can add your website to the queue, without becoming a member; a DMOZ editor must review submissions in the queue before it gets included into their directory.