The complex internal structure of the Sun can now be studied in detail through helioseismology and neutrino astronomy. The VI Canary Islands Winter School of Astrophysics was dedicated to examining these powerful new techniques. Based on this meeting, seven specially written chapters by world experts renowned for their teaching skills are presented in this 1996 volume. With a clear and pedagogical style we are shown how the internal composition (density, He abundance, etc.) and dynamical structure (rotation, sub-surface velocity fields, etc.) of the Sun can be deduced through helioseismology; and how the central temperature can be inferred from measurements of the flux of solar neutrinos. This volume provides an excellent introduction for graduate students and an up-to-date overview for researchers working on the Sun, neutrino astronomy and helio- and asteroseismology.