Specialized search engines are one more tool to include in your SEO arsenal
. Unlike general-purpose search engines, specialized search engines index pages for particular topics only and very often there are many pages that cannot be found in general-purpose search engines but only in specialized ones. Some of the specialized search engines are huge sites that actually host the resources they link to, or used to be search directories but have evolved to include links not only to sites that were submitted to them. There are many specialized search engines for every imaginable topic and it is always wise to be aware of the specialized search engines for your niche.