Speciality search engines definition This is a search engine that is focused on one or two particular specialty search engines or categories, for example Yell.com, Yell uses categorise to make It easier to find the information that is placed into the site. This type of search engine only works for a particular type of subject and display. You can find engines devoted to such diverse topics as computer research papers, file and medical research sites. This search engines is similar to directories because a directory search engines like Yell.com uses Categories to help searches to be found easier.