The U.S. Defense Advance Research Projects Agency (DARPA) launched a the MEMEX project to design advanced search tools that could be also used to scan the deep web, which isnt indexed by Google and other commercial search engines. The Pentagons research agency gave Scientific American a preview of the powerful search engine and explained its use in the fight against cybercrime. The most popular subset of the Deep Web is the Tor network, an anonymizing network that is accessible only by using specific software.”]
Source: https://securityaffairs.co/wordpress/33336/cyber-crime/darpa-memex-deep-web.html