The Andromeda Galaxy, or M31, is an attractive galaxy for astronomers. It is close to us, it is of about the size of our galaxy, it provides some intriguing observational puzzles because the galaxy is nearly edge-on, and many objects can be studied in detail, because they are still sufficiently bright. With the current developments in instrumentation with which increasingly detailed studies of the Andromeda Galaxy can be made, this book provides a solid foundation for the start of new observations. This book is a mine of information about M31. It can be used as a reference by insiders, and at the same time it provides easy access for newcomers to the field.