Do aliens exist?
Possibly, but so far there is no evidence.
Various programs to search for extraterrestrial life signals have existed going back to about the 1960s. SETI is the most prominent but there have been many more recent programs trying to listen for signals from alien worlds. So far, all has been quiet and no truly extraterrestrial radio signals have been found.
Another initiative is trying to send a signal out from Earth to any possible aliens to see if we get a response. However, some scientists are concerned that this could bring unfriendly conquering aliens to our doorstep! Others, think the risk is worth it.
On the other hand, nearly 1000 planets have been discovered in the last few decades and some could have the right factors for life, including: being in the goldilocks zone, favourable atmosphere, size, large enough mass. But supporting primitive simple life, like say algae or simple bacteria, is a long evolutionary step from a planet that supports "intelligent life".
Also, in spite of hundreds of UFO reports, no extraterrestrial vehicles or other tangible evidence has ever been found. And, it seems unlikely that "The Government" is hiding the truth from us! Time will tell......its not impossible.