Statistical thermodynamics serves as a bridge between the universal yet macroscopic-phenomenological laws of thermodynamics and the mechanical or quantum mechanical properties of molecular building blocks. Qualitative considerations regarding the relationships between entropy and molecular disorder or the distribution of energy among individual molecular degrees of freedom are already familiar to chemistry students from introductory lectures. However, a correct representation of these relationships requires a certain formal effort. This book has been written as an introductory text for chemistry students with limited mathematical knowledge, for whom it is still important to understand and learn to apply the methods of statistical thermodynamics.