Web browsing traffic is encrypted and routed through random proxy servers, making it harder to figure out the true IP address of a computer. Tor is a critical tool for activists and dissidents, as it provides a stronger layer of privacy and anonymity.
But some functions of Tor have also been embraced by cybercriminals, which has prompted interest from law enforcement. Thousands of websites run as Tor "hidden" services, which have a special ".onion" URL and are only accessible using the customized browser.
The Silk Road, the underground market shut down by the FBI in October 2013, is one of the most famous sites to use the hidden services feature.
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