Do you believe in UFO?

I personally believe in UFO. But all my friends do not believe in it. I strongly believe because as our huge space, there would probably existing lot of different civilisations. So, some UFO comes from far far planet. to come to earth and exploration is their best technology. In the future, they will explore earth more and more. I would like to know your opinion about it and also too curious about the answers of those who dont believe in UFO...