This book is a collection of papers by four internationally known speakers who explore some key areas in solar physics. O. von der Lühe discusses new techniques that are being developed for observing the sun at high spatial resolution and which have played a key role in most of the recent discoveries about the Sun. Egidio Landi Degl'Innocenti describes the magnetic field that dominates much of the structure we see and many of the active phenomena on the Sun. An understanding of how to measure the field is important. New solar telescopes in Europe and the United States have led the way in the present revolution in the understanding of the sun and important new breakthroughs are expected from LEST. In particular, the post-focus instrumentation has been crucial, and this is detailed by Hubertus Wohl; finally Pierre Mein writes about the solar atmosphere, which is now known to be a dynamic atmosphere with many puzzling features.