Directories are important tools in building link popularity and as a result help improve search engine ranking. They are an excellent source of inbound, one-way links, which are the most powerful types of links to help build link popularity.
There are a multitude of varied directories on the web at present. They range from general directories that include categories for almost everything, to specific directories that contain categories to match specific area/s of interest e.g. web sites about fishing. It is helpful to get your web site listed in as many directories as possible as this will help you beat the competition in rankings.