This is a picture of the common type of sander you'll find in any shop. This particular model has two surfaces: the disk sander, which is the round sanding surface, and the belt sander. This section will concentrate on the belt sander.

Many sanding machines have vacuums attached to catch the dust produced from sanding. Wood and aluminum dust isn't a problem but other materials can produce toxic dusts or dusts that cause allergic reactions in people. PC boards, which are made of fiberglass, are a good example of this and should only be sanded on machines with vacuums attached.