I 'believe in UFOs' to the extent that I believe that people see unidentified objects and interpret them in ways which suggest there's something unusual going on. I'm more sceptical about explanations that they're visiting aliens, though. It's a possibility, but so are hallucinations and misinterpretations of natural or man-made phenomena, which are far more likely. It's also interesting that UFO reports have occurred for centuries, being interpreted differently according to what's culturally acceptable. So in the 1890s there were reports of unidentified airships, for example. And the phenomena of alien abductions has similarities with medieval (or later) accounts of fairy kidnaps.