"Andromeda is the nearest major galaxy to our own Milky Way Galaxy. Our Galaxy is thought to look much like Andromeda.
Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of
billions of stars that compose it. The several distinct stars that surround Andromeda's image are actually stars in our Galaxy that are
well in front of the background object. Andromeda is frequently referred to as M31 since it is the 31st object on Messier's list of
diffuse sky objects. M31 is so distant it takes about two million years for light to reach us from there."
NASA  APOD

This image shows both M31 and M32.  Did you know that Andromeda is moving toward us and will some day merge/collide
with the Milky Way?