Dmoz, otherwise known as the Open Directory Project (ODP) is a directory listed on the web that many businesses want to get their website listed in. The reason for this is that they believe by doing this, a backlink will be created to their site, from a site they believe the search engines to think has authority. This negative view from some people comes from the fact that they expect a different service to the one that is truly offered.
Its main purpose is to catalogue the web into a series of sites that are unique. What is meant by this is that the websites listed do not offer all of the same services. The volunteer editors for this project check on this issue, aswell as following links on other sites and using search engines to find suitable sites to add to the directory.
The main point of Dmoz is that it does not provide a listing service to webmasters, its editors just ask for suggestions from the public as to which websites to include. This however leads to some webmasters frustrations because less than half of the publicly suggested sites are included in the directory.