Collective motion is a manifestation of emergent phenomena in mediumheavy and heavy nuclei. A relatively large number of constituent nucleons contribute coherently to nuclear excitations (vibrations, rotations) that are characterized by large electromagnetic moments and transition rates. Basic features of collective excitations are reviewed, and a simple model introduced that describes large-amplitude quadrupole and octupole shape dynamics, as well as the dynamics of induced fission. Modern implementations of the collective Hamiltonian model are based on the microscopic framework of energy density functionals, that provide an accurate global description of nuclear ground states and collective excitations. Results of illustrative calculations are discussed in comparison with available data.