These two databases each claim to have 1.5 million fully indexed Web pages. Open Text Index , which says it has 1.3 million, is a close follower. The size of an engine's database has a big impact on the success of your search. In several cases, I didn't get any hits at all. Generally, the smaller the database, the fewer hits I received.
Most engines restrict themselves to indexing the Web itself.
InfoSeek and Excite go a few steps further than the rest by also indexing Usenet newsgroups. For a fee, InfoSeek will also let you search a bunch of handy non-Internet databases. It's all in the index Web spiders do more than just collect URLs. They also collect information about each page. The search engine's back-end software uses this information to create an index, which is what you're actually searching when you submit a query.