The advent of modern techniques of observation in the world of amateur astronomers increases their potential to participate efficently to scientific programs. In particular, spectrography is a new, quickly developing tool for amateur astronomers. Moreover, amateur astronomers have more and more possibilities to access telescopes with diameters above 50 cm, either in professional observatories or belonging to associations. These improvements allow professional and amateurs to undertake fruitful collaborations and common meetings. This book collects the lectures given by professional for...