In this talk I will discuss some of the physical features found in the electronic transport in Mesoscopic systems. These are
(i) the quantization of the charge relaxation resistance in a quantum capacitor,
(ii) the magneto-field asymmetries of the current beyond linear response, and
(iii) the non-linear fluctuation relations in a system where detailed balance is explicitly broken.
I will do special emphasis about the importance of considering a gauge invariant transport theory to correctly treat the electronic transport in these systems.