The purpose of this textbook is to introduce the student to a basic area of mac- scopic physics, namely the statistical mechanical study of the different phases of matter, as well as the phase transitions between them. Although many books on statistical physics, for both equilibrium and non-equilibrium systems, are already available, they largely differ in contents. This generally re ects not only the diff- ent interests of their authors, but also the epoch in which they were written. For instance, the early books did usually devote much space to problems of the solid state, whereaslater ones...