In the world of commercial search engines, trade secrets abound. Help files tend to be general in nature when explaining how the technology works. Several Web indexes are powered by the Inktomi index. These Web indexes tap into the same index, though results may be slightly different as Inktomi provides ways for its partners to use a common index yet distinguish themselves. There is no way to query the Inktomi index directly, as it is only made available through Inktomi's partners with whatever filters and ranking tweaks they may apply.
Web indexes are most useful to find Web pages on a specific topic.
Metasearch engines do not maintain any local database but provide a convenient interface that simultaneously sends your query to several Internet search engines and returns the complete set of results. UC Berkeley Guide to Meta-Search Engines lists some of the better MetaSearch engines. While this approach can save you considerable time, Metasearch engines are mainly useful for simple searches as their search software do not take full advantage of the advanced search features of the individual Web indexes. Searching individual Web indexes thus often may be preferable to take advantage of their advanced search features. There's a big problem with most search engines, and it's one most people aren't even aware of.