The unification of space and time into a four-dimensional continuum, introduced by Hermann Minkowski, provides the natural mathematical framework for Einstein’s theory of special relativity. In this chapter, we develop the concept of Minkowski space, where events are described by four-vectors and the invariant spacetime interval replaces the Euclidean distance of classical geometry. The geometry of Minkowski space is governed by a pseudo-Euclidean metric, leading to the classification of intervals into timelike, spacelike, and lightlike. The Lorentz transformations emerge as hyperbolic rotations in this four-dimensional space, preserving the invariant interval and defining the causal structure of physical processes. The formalism of four-vectors is systematically introduced for position, velocity, energy-momentum, and force, highlighting their transformation properties and the simplification they bring to relativistic dynamics. Applications to particle collisions and decay processes are discussed, emphasizing the power of Minkowski space in unifying diverse relativistic phenomena. The chapter underscores that the four-dimensional formulation not only provides elegance and clarity but also brings simplicity in solving kinematic problems encountered in high-energy nuclear and particle physics.