Why are fluids put under pressure?

When a pressure is applied on a fluid, which can be either
a liquid or a gas, the pressure is spread out uniformly and the same pressure exists at
all points in the fluid.

Pressure is applied to fluids in
many applications that require the movement of a load but the force cannot be applied
directly to the load. Or in cases where it is easier to apply a small pressure on the
fluid for a long time and have it multiplied by the fluid. Using fluids to transfer
force is also often more efficient than using shafts, strings,
etc.

Some applications where this is made use of include
brakes, pneumatic motors, cable jetting, vacuum pumps among many
others.