This text grew out of notes from a graduate course taught to students in mathematics and mechanical engineering. The goal was to take students who had some basic knowledge of differential equations and lead them through a systematic grounding in the theory of Hamiltonian systems, an introduction to the theory of integrals and reduction. Poincaré’s continuation of periodic solution, normal forms, and applications of KAM theory. There is a special chapter devoted to the theory of twist maps and various extensions of the classic Poincaré-Birkhoff fixed point theorem.