The series of ‘Cool Star’ meetings concentrates on the astrophysics of low-mass stars (with masses similar to that of the Sun and lower), including the Sun. The meeting in St. Andrews, Scotland, was the 15th in this series, and focused in particular on the origin of low-mass stars and their planets, as well as the properties of their atmospheres. This volume provides a comprehensive overview of the science presented by the 350 participants of this meeting. The book is suitable for researchers and graduate students interested in the astrophysics of cool stars and the Sun.