The TOR (the onion routing) browser is a web browser designed for anonymous web surfing and protection against traffic analysis. Although Tor is often associated with the darknet and criminal activity, the browser is often used for legitimate reasons by law enforcement officials, reporters, activists, whistle blowers and ordinary security-conscious individuals.
TOR was originally developed by and for the United States Navy to protect sensitive U.S. government communications. While Tor continues to be used by government it is now an open source, multi-platform browser that is available to the public. The browser uses exit relays and encrypted tunnels to hide user traffic within the network, but leaves the end points more easily observable and has no effect beyond the boundaries of the network.
Although TOR is more secure than most commonly-used browsers, it is not impervious to attack. Malware, such as the Chewbacca Trojan, has successfully targeted the TOR network and browser. The FBI has also breached TOR security, in one case, for example tracking threats associated with a bomb hoax at Harvard across the network.