We review several experimental aspects of ultracold bosonic and fermionic quantum gases in optical lattices. After introducing optical lattices, we use the superfluid-Mott insulator transition of ultracold bosonic quantum gases, to highlight the physics of strongly correlated quantum systems. We discuss the coherence properties and recent measurements of the shell structure in the Mott insulating phase. Subsequently, dynamical interaction effects in the collapse and revival of the matter wave field of a BEC are analyzed, followed by a discussion on interacting fermions, superexchange-mediated spin-spin interactions and quantum noise correlation interferometry in optical lattices.