M31 used to be called the Andromeda Galaxy or MGC 224. M31 is an acronym for Messier 31. A spiral galaxy "close" to the Milky Way. It is the home to most of the life in the Universe. Originally named after princess Andromeda. It is roughly 220,000 light years across, wich is more than double the size of the Milky Way.
It is the home of the Areseld BO.