In the first part, we shall recall the definition of Hamiltonian systems defined with respect to a Dirac structure. Then we shall recall how these systems may be extended in order to describe open physical systems by including pairs of external variables (interface variables) called port variables. We then show how these systems may be composed, thereby defining complex systems.

In the second part, we shall recall that the Port Hamiltonian systems allow to express systems of balance equations (conservation laws with internal or boundary source terms) and define the class of Dirac structures associated with these systems. We shall then present some examples stemming from Engineering applications.