The simulation of the transport of light through non-empty media is of great importance in volume visualization applications. For low-albedo media, the Single Scattering Model is a good approximation, and it is used extensively. Its derivation is presented here in detail. The model establishes the light that reaches an observer through a participating media from a given direction. The resultant expression is an integral of light contributions over a line of sight properly scaled by their correspondent attenuation factors. In the general case, the integral has not closed form solution. Some simplificative assumptions that allow to compute it analytically are exposed here. Finally, it is shown how the Single Scattering Model may be applied both to ray-casting and to splatting algorithms, and how it is used to shade surfaces in direct volume rendering.