Examples of web directories are Yahoo and Lycos. Web catalogs are database that are compiled from the web and stored on the web site. Users need only to log on to the web catalog and search for it. Weak points are lacking of a real search engine and information might be dated. Offline databases are compiled and stored offline on CD-ROM or other media.
Weak points are the same as web catalog.
Yahoo search is a typical search engine. Users can enter in the search keywords with or without Boolean operators. A good search strategy calls for keywords as long and as specific as possible. If the result is not what the user is looking for, then broaden the search. Advance search features are also available from the web site.