Abstract: The Hall effect is the production of a voltage difference across a conductor, transverse to an electric current, in a presence of a magnetic field in the normal direction. At very low temperatures,  the (quantum) Hall conductance as a function of the strength of the magnetic field exhibited a staircase sequence of wide plateaus. The successive values of the Hall conductance turn out to be integer multiples of e^2/h, with remarkable precision (here e is the elementary charge and h is Planck's constant). This quantization can be understood in terms of topological invariant given by the Kubo-Streda formula. I will discuss the properties of the Kubo-Streda formula and its derivation in the adiabatic setting.