Pascal's Law states that when pressure is applied to a confined fluid, the pressure change is transmitted equally in all directions throughout the fluid. This principle means that any increase in pressure at one point in the fluid will result in an equal increase in pressure at every other point, regardless of the shape or size of the container. This law is fundamental in understanding how hydraulic systems work, such as hydraulic lifts and brake systems. By applying a small force over a small area, a much larger force can be generated over a larger area, allowing for efficient movement and control of heavy objects.