A smoothing plane or smooth plane is a type of bench plane

Plane (tool)

A hand plane is a tool for shaping wood. When powered by electricity, the tool may be called a planer. Planes are used to flatten, reduce the thickness of, and impart a smooth surface to a rough piece of lumber or timber. Planing is used to produce horizontal, vertical, or inclined flat surfaces on...

 used in woodworking

Woodworking

Woodworking is the process of building, making or carving something using wood.-History:Along with stone, mud, and animal parts, wood was one of the first materials worked by early humans. Microwear analysis of the Mousterian stone tools used by the Neanderthals show that many were used to work wood...

. The smoothing plane is typically the last plane used on a wood

Wood

Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

 surface - when used properly, the finish it gives will be far superior to that made by sandpaper or scrapers. The smooth finish is the result of planing the wood off in strips, rather than by successive buffing and scratching.

The smoothing plane is typically 8 to 10 inches long. The throat may be adjusted to a tight opening so as to allow only a very fine shaving and to reduce tearout of the grain to a minimum. The smooth plane is held with both hands. The iron of the smoothing plane is generally sharpened straight across or with a slightly arched cutting edge (or at least with rounded corners) to prevent unsightly grooves from being gouged in the wood surface

Surface

In mathematics, specifically in topology, a surface is a two-dimensional topological manifold. The most familiar examples are those that arise as the boundaries of solid objects in ordinary three-dimensional Euclidean space R3 — for example, the surface of a ball...

as it is planed.