The body of a random orbit-sander is typically ergonomic for comfortable grip and ease of use, it also houses the motor that drives the sanding pad.
The power switch simply turns the sander on and off. On most modern random-orbit sanders the sanding pad won’t start to spin until you start to put some pressure onto the sander.
The palm grip is ergonomic and comfortable to hold, reducing hand fatigue during long sanding jobs and promoting ease of control.
The D-handle is a secondary handle used for sanding.
The barrel grip allows you to hold the sander by the body and manoeuvre it comfortably.
The dust bag collects wood particles as they are sanded off the workpiece. The dust bag is attached to the body of the sander via a vent.
The lip seal – a common feature on many random-orbit sanders – is a rubber seal that prevents sawdust from clogging up the internal motor as well as providing a barrier between your hands and the sanding disc.
The sanding pad is the part of the sander that rotates and oscillates. A sanding disc (or other attachment) is affixed to the sanding pad so that the sander can perform a variety of tasks including sanding, polishing, and stock removal (removal of large amounts of wood by sanding).
A sanding disc is a circular paper abrasive commonly attached to a random-orbit sander.