An important tool in organizing and presenting the plethora of websites available on the internet is the use of Directories – an alternative to Search Engines that links and categorizes sites on the web. The main advantage to Directories as opposed to Search Engines is that directories are edited by humans, whereas search engines simply return automated results based on keywords which may not always be the most effective way to quickly find a website that is apropos to the topic being searched for. Websites are submitted to directories by the webmaster, where they are reviewed by neutral editors, evaluated, sorted into categories, and ranked within category according to relevance. They are then listed in a directory form that is simple to read and navigate for the average browser. For a website to create and maintain high web visibility – and therefore attract a high number of visitors – it is essential to be listed in a number of quality Directories.

The best known directories are Yahoo, Dmoz and Google, but it is worth being aware of the quality of the directory before submitting a site. The average browser will not explore beyond the second or, at most, third page of directory results for their searched for topic, but if the Directory is not of quality some websites listed in those all-important first few pages may not deserve to be there. The usefulness of Directories to return appropriate search results to be valuable to a site is under debate.

If links are being sold across the entire site, that may be indication of a lower quality Directory. Google is one of the worst culprits for targeting sites that sell links, and sites that appear to promote the Google page rank of their pages. This may not be indicative of how relevant a site is to the topic searched for – it is all too easy for crafty webmasters to manipulate keyword SEO to gain a higher Google page rank than their site deserves. This is time-wasting and frustrating for browsers, and may result in them losing patience with the Directory all together. Another common problem with Directories to be avoided is that pages within the site may be linked only internally and not to other, relevant, quality, external pages. Search Engines will not find such pages if they are low on keyword content and they will be skipped over entirely.

Dmoz, the Open Directory Project (ODP,) editors are volunteers – they are naturally third-party neutral and will review and consider each submitted website on its own merits. Each editor applicant is screened for any conflict of interest, so any search results returned by Dmoz Directories can generally be trusted. The main downside to submitting a website to Dmoz is that the submission process can be interminable – although ultimately worth it in terms of relevant traffic directed to any website included in their directory. The Yahoo! Directory rivals Dmoz for size and comprehensiveness, and was in fact Yahoo's initial reason for existence. It has since evolved away from the fundamental classic human edited format of Directories, by instituting crawler-based listings in 2002, but remains a quality Directory that can be trusted. The Yahoo! Directory is very clearly displayed on its homepage. LookSmart, and Zeal – LookSmart's non commercial arm – are other famous examples of quality directories.

For a website to be listed in a trustworthy Directory such as Dmoz or Yahoo! can be one of the most important quality-assurance seals of approval and can be the essential difference between focused and relevant traffic to the site and random hits by frustrated browsers.