The Sun has been an object of scientific interest since the time of the ancient Greeks. The vast amounts of observational data acquired in recent years have led to a greatly enhanced knowledge of the physics of the Sun. With a minimum of technicalities, this book gives an account of what we now know about the Sun's interior, its surface & atmosphere, its relation to the solar system including the earth, & its relation to other stars. The way that solar power is being converted to useful forms of energy is explained. The book is aimed at anyone with a broad science background interested in learning about the latest developments in solar studies, from those at high-school level to the non-specialist professional.