This chapter introduces two types of quantum corrections to the conductivity originating from the wave component of the electron nature. The first is due to interference between different replica of an electron wave function, which appears during the elastic scattering of the electron from impurities. This correction arises when the electron travels along a closed diffusive trajectory; it is called weak localization and is destroyed by magnetic field. Antilocalization is also possible when spin-orbital interaction is involved. The second correction comes from the interference of two different electrons with almost the same energies, both travelling along adjoining diffusive trajectories. This is called Aronov-Altshuler effect.