A machine is fundamentally a mechanical device designed to transmit, modify, or multiply energy and force to perform useful work. These devices operate by converting one form of energy, such as potential or chemical energy, into kinetic energy through a systematic series of components. Simple machines, such as levers, wheels, and inclined planes, represent the most basic principles of mechanical advantage, while complex machines incorporate multiple interconnected parts—such as gear trains, linkages, and hydraulic actuators—to achieve highly specialized functions. The underlying physical principles governing mechanical devices involve the study of kinematics and dynamics, determining how forces interact with physical structures to generate reliable, directed motion.