The Milky Way Galaxy is a fairly ordinary spiral Galaxy containing Spiral Arms, astronomers call it a barred spiral. It is 100,000 light years in diameter and 1,000 light years in thickness. with between 200-400 billion stars and that is a lot of stars. All that makes it a giant galaxy, bigger than other galaxies in its neighbourhood even Great Andromeda Galaxy, M 31 is not as large as the Milky Way.  The Milky Way Galaxy is incredibly old and formed not more than about 1 billion years after the Big Bang and at its centre is an enormous black hole. We don't know if Extraterrestrial aliens are there.