Got a research paper or thesis to write for school? Want to research using the Internet? Good luck. There's a lot of junk out there — outdated pages, broken links, and inaccurate information. Using Google or Wikipedia may lead you to some results, but you can't always be sure of accuracy. And what's more, you'll only be searching a fraction of all of the resources available to you.
Google, the largest search database on the planet, currently has around 50 billion web pages indexed. That's a lot of information. But it's nothing compared to what else is out there. Google can only index the visible web, or searchable web. But the invisible web, or deep web, is estimated to be 500 times bigger than the searchable web. The invisible web comprises databases and results of specialty search engines that the popular search engines simply are not able to index.
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