A staircase is an example of the inclined plane simple machine. A spiral staircase, however, is categorized as a screw. Another common example of an incline plane is a ramp.
Inclined planes are simple machines because they make it easier for heavy items to travel in an upward direction. Other kinds of simple machines, aside from the inclined plane and screw, include the lever, wedge, pulley and wheel and axle. Some common examples of the lever simple machine include the baseball bat and seesaw. Rolling pins and tires are types of wheel and axle machines, and axes and knives are examples of wedges.