The Planck mass is a fundamental unit of mass in the field of physics, specifically in the context of quantum mechanics and general relativity. It is defined as approximately 2.18 \times 10^-8 kilograms. This mass is significant because it represents a scale at which the effects of quantum gravity become important, bridging the gap between the very small (quantum particles) and the very large (cosmic structures). In the system of natural units known as Planck units, the Planck mass is derived from three fundamental constants: the speed of light in a vacuum, the gravitational constant, and the reduced Planck constant. These units help physicists understand phenomena where both quantum mechanics and gravity play a role, such as in the study of black holes and the early universe.