(From doi: 10.1016/j.physrep.2004.11.002): We explore the prospects to control by use of time-dependent fields quantum transport phenomena in nanoscale systems. In particular, we study for driven conductors the electron current and its noise properties. We review recent corresponding theoretical descriptions which are based on Floquet theory. Alternative approaches, as well as various limiting approximation schemes are investigated and compared. The general theory is subsequently applied to different representative nanoscale devices, like non-adiabatic pumps, gates, quantum ratchets, and transistors. Potential applications range from molecular wires under the influence of strong laser fields to microwave-irradiated quantum dots.