A router is a woodworking tool used to route out (hollow out) an area in the face of a piece of wood. Modern routers are often used in place of traditional molding planes or spindle molder machines for edge decoration (molding) of timber.

Router bits come in hundreds of varieties to create either decorative effects or joinery aids. Generally, they are classified as either high-speed steel (HSS) or carbide-tipped, however some recent innovations such as solid carbide bits provide even more variety for specialized tasks.

Bits can be classified as edge bits or non-edge bits. Edge bits have a small wheel bearing to act as a fence against the work in making edge moldings. Non-edge bits require the use of a fence, either on a router table or attached to the work or router.

Bits also differ by the diameter of their shank, with ½ inch, 12 mm, 10 mm, 3/8 inch, 8 mm and ¼ inch and 6 mm shanks (ordered from thickest to thinnest) being the most common. Many modern routers allow the speed of the bit's rotation to be varied. A slower rotation allows bits of larger cutting diameter to be used safely. Typical speeds range from 8,000 to 30,000 rpm.