The book summarizes research into the fundamental properties of the outer Milky Way (including its mass, scale and rotation properties) and covers topics such as spiral structure, the interstellar medium, star formation, satellites of the Milky Way and the outer parts of some nearby galaxies. It contains new work on the outer rotation curve of the Milky Way, first results of a new low frequency galactic disk survey, new results on the scale of the Galaxy (the distance of the Sun from the center and the relation of the disk of the Milky Way to the halo). This is the first volume specifically dedicated to outer galaxy research. Professional astronomers and astrophysicists as well as graduate students will welcome this book as a guide in understanding the outer parts of the Milky Way and also other galaxies.