content: It was developed by the US govt for their own use, but they quickly realized that if only government personnel used it, it would be much easier to identify their activity. Because of that they released it to the public, as it adds some security through obscurity, and provides a modest bump in bandwidth.  Technically speaking, it has no backdoors, but it does have vulnerabilities. The US govt operates nearly all of the exit nodes, meaning that chances are high that any given data sent using tor's protocols is no more secure than standard HTTPS. However, its nearly perfect security if the govt has no reason to care about you. Tor is ideal for keeping your metadata out of the hands of corperations like google that will sell it to the highest bidder.  Long story short, tor has no backdoors, but the US govt is kinda like the locksmith you hired last month to re-key the front door.