You will never know for sure if they're real (I think) unless you see one in the flesh (which I haven't).
Might I add, there are tens of thousands of pictures, and thousands of videos of UFOs from around the world. There are radar sightings confirmed by civilian and military pilots, a few of the Appollo astronauts + a steady stream of astronauts up until the present. Mass sightings like the Belgium UFO, pheonix and countless others.
Look, some of this stuff may not be true -but all of it?
I think there's proberly plenty of 'proof' - but how can you know what is real and what isn't?
Maybe aliens seem like a long shot, but we just don't have the experience to judge how likely/unlikely a possibility it is that they are visiting us. Makes sense that an intelligent race would want to study another, especially when they (us) are just beginning to rise into a technological age.
Some people rule them out because of the lightspeed barrier, space being so vast, but once again -how do we know they are limited by physical laws? UFO's have been observed (on radar as well!) manouvering such that they must be circumventing the law of inertia, as if they have no mass!?!(right angle turns at thousands of km/h, accelerations that would rip a manmade aircraft apart - let alone the pilot) Not defying the law i doubt, but finding a way around it. So maybe they find ways around lightspeed as well.
Sounds like fantasy, because for us it is fantasy, but in another thousand years....? Like Jules Verne writing about a rocket to the moon not that long ago
Mate, I am a believer - no I can't prove it, no rectal probe r nothin/
Check out Bill Chalker on the net, should see a link to 'The Oz Files' which is the RAAF (Aussie) files on ufos from the 50s through to the 80's. Some pretty amazing stuff there. Just be mindfull that a lot of websites on the topic attract 'cranks' who 'want to believe' at all costs.
Happy hunting