Centrifugal force is the force which describes the outward pressure that is exhibited around an object rotating around a central point. Its definition is based on a Latin phrase which means "fleeing the center," an accurate description based on what is being observed. There are some physicists who claim that true centrifugal forces do not exist, that an object's reaction to such a force can be explained by other means.
One possible explanation for centrifugal force rests in Newton's law of inertia. This law states that an object in a uniform motion tends to stay in that same motion unless there is pressure exerted by an outside force. For example, a ball being twirled around on a string would tend to go in a straight line if not for the string and the force the string puts on the ball. Therefore, the ball, instead of going in a straight line, goes in a circular motion around the center of the pivot.
This explanation, why easily understandable, does not explain all aspects of centrifugal force. For example, why does the force still exist when there is no string? In such cases, there is likely still going to be an outside force exhibiting pressure on the object, keeping it from going in a straight line. This is likely to include a cylinder.
Though the concept is not readily understood, the benefits of what many people refer to as centrifugal force are used for the benefit of mankind. For example, centrifugal force is what dries clothes in a dryer. Along with the heat that is used, the dryer also spins the clothes, much like a washing machine does, to get the majority of water out of them before the dryer finishes the job.
The medical community often uses a device specifically for creating a centrifugal force -- something commonly called a centrifuge. This spins blood samples to separate the solids from the liquids, which makes it better for detecting certain conditions. With the blood spinning, the heavier portions tend to settle toward the bottom of the vial.
In the end, centrifugal force may yet be explained away. However, the nice thing about the phenomenon is that it is not necessary to fully understand it in order to take advantage of it. The effects are clear and the benefits derived from the force are numerous.