There are many specialized search tools that exist to locate the information on the invisible web. Some of these topic-specific search engines have been gathered into directories by a number of companies, agencies, and individuals. Below are a few of the most noteworthy of these directories. These are designed to guide you to the appropriate search engine, not to the specific information that you may need. Databases Much of the invisible web consists of databases, or collections of targeted files or links, that have their own search engines.
Some sites offer free information while others requires registration, a fee, and a password.
This is sampling of some databases that are particularly useful for librarians. Digital Libraries Digitial libraries consist of text documents, maps, images, and sounds that have been digitized for electronic access. Usually these collections include their own internal search engine.