A web directory is not a search engine and does not display lists of web pages based on keywords; instead, it lists web sites by category and subcategory. Most web directory entries are also not found by web crawlers but by humans. The categorization is usually based on the whole web site rather than one page or a set of keywords, and sites are often limited to inclusion in only a few categories. Web directories often allow site owners to submit their site for inclusion, and have editors review submissions for fitness.
This list of Top Web Directories contains the Top Directories rated by the quality of inbound links each directory has. The ILQ Rating Score is taken from the number of inbound links each directory has from DMOZ, EDU and GOV sites. Here is more info on how the ILQ Ranking system works.