Hydraulic systems use liquids to transmit power and perform work. They operate based on Pascal's principle, which states that pressure applied to a confined fluid is transmitted equally in all directions. This principle allows hydraulic systems to lift heavy loads, making them essential in various applications like construction and manufacturing. Common examples of hydraulic systems include hydraulic lifts, excavators, and braking systems in vehicles. These systems typically consist of components such as pumps, cylinders, and valves, which work together to control the flow and pressure of the fluid, enabling precise movement and force application.