This third volume in the comprehensive Digital Electronics series, which explores the basic principles and concepts of digital circuits, focuses on finite state machines. These machines are characterized by a behavior that is determined by a limited and defined number of states, the holding conditions for each state, and the branching conditions from one state to another. They only allow one transition at a time and can be divided into two components: a combinational logic circuit and a sequential logic circuit.The approach is gradual and relatively independent of each other chapters. To facilitate the assimilation and practical implementation of various concepts, the book is complemented by a selection of practical exercises.