A router is used to finish edges and given the right bit, a router can plane edges, cut multi-curved mouldings, produce relief panels, rabbet and dovetail for professional joints, trim formica and cut delicate grooves for professional inlay work.
In its simplest form, a router is just an electric chisel. But it's one of the most versatile power woodworking tools around, able to plane, saw, shape, groove, mortise, trim, dado, and more. It's usually operated as a handheld tool, but it also can be mounted to a stationary table for even greater versatility. Home Improvement Encyclopedia