A random-orbit sander is a hand-held power tool popular with carpenters, cabinet makers and many other woodworking professions.
A typical random-orbit sander consists of a mains or battery powered motor housed inside an ergonomic body to which a sanding pad can be attached.
A sanding disc is then attached to the pad via either a “peel and stick” or “hook and loop” method. For more information see the page, What are sanding discs?
The motor drives the sanding disc and causes it to rotate at high speed, whilst simultaneously moving in an elliptical orbit so that no single spot on the disc travels the same path twice.
Because the pad spins at high speed whilst simultaneously moving in an elliptical orbit, it eliminates the swirl markings common with other types of power sanders.