machines

Machines are devices that use energy to perform work, change the magnitude or direction of a force, or control the movement of objects and systems. By converting energy from one form to another, they enable tasks that are difficult or impossible to accomplish with human effort alone. The study of machines spans physics, engineering, and applied sciences.

Historically, many devices began as simple machines—the lever, inclined plane, wedge, screw, pulley, and wheel and axle—that reduce effort through mechanical advantage. When combined, these form complex machines such as clocks, tools, and engines. Energy sources have evolved from human and animal power to wind, water, steam, electricity, and chemical fuels.

Modern machines comprise energy sources, mechanisms, actuators, and control systems. Mechanisms include gears, linkages, cams, and belts that shape motion. Actuators—electric motors, hydraulic and pneumatic cylinders, combustion engines—provide power to move components. Controllers, ranging from manual levers to computerized sensors and software, regulate operation and ensure safety and precision. Complex machines integrate multiple simple machines and subsystems.

Industrialization and the digital era expanded machine use from production lines to everyday devices. Computing machines, robotics, and automated systems increasingly perform tasks with high accuracy and speed, often under feedback control. Machines are crucial across manufacturing, transportation, energy, healthcare, and communication.

Limitations include maintenance needs, wear, energy efficiency limits, and reliability. Ethical and environmental considerations address resource use, emissions, and labor impacts. Overall, machines continue to extend human capabilities by enabling new techniques, reducing manual labor, and enabling exploration and innovation.