Having studied the UFO phenomenon for close to 25 years and having interviewed people who have seen them, or who have been abducted I can say in all honesty...they do exist!
I have seen a lot of pictures of them and, granted, some of the pictures I have seen are very questionable, but others aren't. I have seen video clips made by news services that are proof positive that we are being visited...or, at least...observed. What was flying in those clips were definitely not known aircraft.
The government is covering the UFO crash in Roswell, NM in 1947. They have changed the story on that at least three times and each time it gets more bizarre and unbelieveable. I have done business with a gentelman who was a B-24 Bomber Pilot in WW2. He was stationed at the air base in Roswell in 47. I asked him if the stuff they found was a "weather balloon". His comment? "Not on your life!"
So...the UFO's are real and we are being visited. Their purpose here is unknown to us, but probably known to the government. There is a lot of speculation about why they are coming here, but none has been proven. We are probably safe in saying their visitations are not of the hostile nature and probably more scientific? We may specualte that maybe they are thousands of years ahead of us in technology and have, maybe, recently discovered us and they are curious? About all we can do is sit back and wait to see what happens?