We review the basics of Thermal Relativity Theory and describe many of the novel physical consequences, including the $corrections$ to the Schwarzschild black hole entropy. One of the most salient results is the existence of a minimal area ${ L_P^2 over 4 pi} $, where $ L_P$ is the Planck length. The brief review paves the way to the study of the thermal relativistic analog of Lorentz transformations. A careful examination of these transformations imply that entropy is observer $dependent$ and that one must also include negative masses, entropy and temperature in the formalism. A review of the literature on negative masses, entropy and temperature follows. In special relativity one has the equivalence of mass and energy. While in thermal relativity one finds an equivalence of proper thermal mass $ {cal M } $ (not to be confused with ordinary mass) and proper entropy $ {bf s }$. We conclude with a brief description of Born's Reciprocal Relativity Theory (BRRT), based on a maximal proper-force, a maximal speed of light, inertial and non-inertial observers, and explain how to extend the formulation of thermal relativity described in this work to cotangent spaces.