Before submitting your website to search services, it is important to explain and understand a few basic terms. The generic term search services comprises all websites which help users to locate information.
Often, the term search engine is misused to describe pure search engines, as well as directories. In fact, they are not identical; the difference lies in the way result listings are generated.
Search engines, also referred to as spiders or web crawlers, regularly visit websites to create catalogues of web pages. Search engines like Google create their result listings automatically. They simply crawl over the web and let humans check the search results. This enables engines to automatically detect changes which you might have made to your website. Website changes influence the way your site is listed in the search result pages. Many elements can play a decisive role here: page titles, text blocks, or other page elements. As engines work automatically and index a large amount of web pages, they often find information not listed in directories (see below). Search engines usually accept all submitted websites.
In contrast to search engines, directories are not created automatically, but by editors. Here, a website is submitted and linked to one or more meaningful categories. As directories are usually created by experienced editors, they generally produce better (at least better filtered) results. The best-known and most important directory is Yahoo.
In directories like Yahoo, result listings are influenced by humans. Either you enter a short description of you website, or the editors discussing our site will do that. When searching, only these descriptions are scanned for matches, so that website changes do not affect the result listing at all. Criteria which improve your ranking in a search engine's listing are not necessarily useful to improve your position in a directory's listing. Usually only websites which comply with certain quality standards are accepted. A good site (with quality content) has better opportunities than a "bad" site (with poor content).