S INGLE discrete classes of particles in SV experiments generate various sourcesof information on their sedimentation, diffusion, and buoyant molar mass. These are systematically explored in the present chapter. The term “discrete” highlights that all particles of this class in suspension are uniform with respect to size, mass, density, and friction. They may be an ensemble of states, for example, with regard to conformation, but interconvert fast on the time-scale of sedimentation to present only an average behavior. The single discrete class of particle is contrasted by the idea of a continuous distribution of particles introduced in Chapter 3, which could be thought of as an essentially infinite number of particle classes, each with slightly different parameters.