Well, not exactly. There are probably several thousand different key combinations for a given lock cylinder. The key for your lock will fit some other locks using the same cylinder. Of course, this means that there are other keys that will open your lock. The trick, of course, is that the chances of someone else's key working your lock is small enough that for all practical purposes, you have a unique key.[/QUOTE]

The same is true for your front door, your car, etc.