How unique is UUID?

Question

How safe is it to use UUID to uniquely identify something (I\'m using it for files uploaded to the server)? As I understand it, it is based off random numbers. However, it s

Answer 1

UUID schemes generally use not only a pseudo-random element, but also the current system time, and some sort of often-unique hardware ID if available, such as a network MAC address.

The whole point of using UUID is that you trust it to do a better job of providing a unique ID than you yourself would be able to do. This is the same rationale behind using a 3rd party cryptography library rather than rolling your own. Doing it yourself may be more fun, but it's typically less responsible to do so.