Having described the transverse quantization of motion into subbands in lowdimensionalmesoscopic systems, we will now see how these are utilized to describe coherent transport through devices like quantum billiards within the effective independent-electron picture. This is done within the Landauer-Büttiker theory of transport in multiterminal structures, which relates the scattering matrix of the system to its electrical conductance. After presenting the general framework, we focus on the linear response regime of transport.