The purpose of this contribution is the description of the progress in theoretical investigations on electronically excited states in connection with photodynamical simulations made within the last years and to provide an outlook on the scope of future applications and challenges. An overview over excited-state phenomenology is given and the applicability of different computational methods is discussed. Both electronic structure- and dynamics methods are considered. The examples presented comprise the explanation of the photostability of individual DNA nucleobases, the photodynamics of DNA including excitonic and charge-transfer processes, the primary processes of vision and the broad field of photovoltaics, photodevices, and molecular machines.