Tor (the union routing) browser Alpha was developed by the United State Navy and the main purpose for its development was to protect sensitive United State’s government communication. Other than the fact being developed by the U.S. Navy, Tor Browser is also designed for anonymous web surfing and protection against traffic analysis.
While it is still being used by the U.S. government, Tor is now an open source, multi-platform browser available for basic internet surfing for individuals like you and me. It is also used for licit reasons by law enforcement individuals and security-conscious personnels even though is often classified as being associated with darknet and criminal activities such as cyber-terror.
The browser hides the users traffic within the network by use of existing relays and encrypted tunnels, but it leaves the end point open and has no effects beyond the boundaries of the network. Although being more secure compared to other browser, it tolerates attacks and it is even known to once being attacked by malware, such as the Chewbacca Trojan.
Tor is not good in preventing an online service from detecting when it is being accessed through Tor browser. Although Tor can protect a user’s privacy, it cannot hide the fact that you are using it. Thus make some sites to restrict allowance through Tor. A good example is MediaWiki TorBlocker extension which automatically restricts edits made through Tor.
Hackers may try to de-anonymise the user through exploitation of vulnerable software on the user’s computer. NSA came up with a technique that targeted vulnerability, the Egotistical-Girraffe in an outdated Firefox browser bundled with Tor package, the main objective was to target Tor users for close monitoring under XKeyscore program. In academic research attacks against Tor are dormant and welcomed by Tor Project itself.
This is all that an internet lover who would want to switch from maybe Chrome, Firefox, Opera or any other browser to Tor browser needs to know at the beginning stage. If Tor feature please your needs, well, I suggest you switch to it right away.