Pascal's Law, named after the French mathematician and physicist Blaise Pascal, states that when there is an increase in pressure at any point in a confined fluid, there is an equal increase in pressure at every other point in the fluid. This principle forms the basis for the functioning of hydraulic systems.

In a hydraulic system, a small force applied to a small piston can be amplified or transmitted to a larger force through a larger piston by utilizing the principles of Pascal's Law. This allows for the amplification of force, making hydraulic systems effective in various applications such as machinery, automotive braking systems, and hydraulic lifts.