In Chap. 3, we introduced the principles of nonrelativistic mechanics. The current chapter is devoted to the principles of special relativity and relativistic mechanics. We begin by pointing out the inadequacies with the Newtonian concepts of space and time when speeds approach that of light. An elementary introduction to special relativity and relativistic kinematics follows. In Sect. 4.10*, we introduce the Minkowski geometry of space-time and use it to formulate relativistic kinematics and dynamics.