The universal dispersion model is a collection of dispersion models (contributions to the dielectric response) describing individual elementary excitation in solids. All contributions presented in this chapter satisfy the basic conditions that follow from the theory of dispersion (time reversal symmetry, Kramers--Kronig consistency and finite sum rule integral). The individual contributions are presented in an unified formalism. In this formalism the spectral distributions of the contributions are parameterized using dispersion functions normalized with respect to the sum rule. These normalized dispersion functions must be multiplied by the transition strengths parameters which can be related to the density of charged particles. The separation of contributions into the transitions strengths and normalized spectral distributions is beneficial since it allows us to elegantly introduce the temperature dependencies into these models.