Thomson scattering is a very powerful diagnostic which is applied at nearly every magnetic confinement device. Depending on the experimental conditions different plasma parameters can be diagnosed. When the wavelength is much smaller than the plasma Debye length, the total scattered power is obtained by an incoherent summation over the scattered powers of the individual electrons. The scattering spectrum in this case is a reflection of the electron velocity distribution, from which local values for the electron temperature and density can be derived.