Most frequent types of magnetic contributions to specific heat Cm at low temperature are analyzed, starting with the conduction electron interactions which enhance the effective electron mass. The main features of the thermal Cm(T) dependence: below, above and at a magnetic phase transition, are then described together with the information that can be extracted from that behavior, as well as the effect of control parameters like magnetic field, pressure, or alloying. Typical Cm(T) anomalies originated in different electronic interactions like: Crystal Electric Field, Spin Glass, and Kondo effect are analyzed. The thermal properties of Strongly Correlated Electrons are discussed in the frame of Non-Fermi liquid behavior of Heavy Fermion. The complementary information that can be extracted from the thermal evolution of the Entropy in each case is also discussed. Fil: Sereni, Julian Gustavo Renzo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina