abstract: Originally, Floer homology had been invented in order to prove the Arnold conjecture on the existence of symplectic fixed points. Whereas the main aspect was that Floer homology encodes classical topology of the underlying symplectic manifold, subsequent developments have found additional important and non-classical structures such as the pair-of-pants ring structure which allow further applications in Hamiltonian dynamics. One aim of the lectures will be to introduce Floer homology together with this additional ring structure. Applications to the Hamiltonian action spectrum and the study of the Hamiltonian dieomorphism group will be presented. Moreover, also the relation to the topology of the free loop space will be covered.