The plane is the cabinetmaker´s most important tool and was used already by the Romans.
The main parts of a plane are the body and the iron. The body is made from metal or from wood. For wooden planes hard and evenly grained woods like beech, maple and whitebeam are used. Sometimes the sole of the body is a harder wood, like hornbeam.
When planing you aim at cutting long shavings from the whole length of the work piece. To succeed you need some kind of jig for the cutter; to do it with an unguided chisel or knife is next to impossible.
A plane with the steel wedged into the body makes it possible to cut shavings with even thickness. With the sole holding the wood down in front of the iron there is no risk for splitting or tearing the surface. The wedge also brakes and guides the shaving out of the plane. Jointers and finishing planes have a chipbraker attached to the iron to reduce tear out when planing against the grain.
When planing, as opposed to in knife or ax work, you decide the exact thickness of the shavings; by adjusting the space between the sole and the iron. On wooden planes you deepen the cut by knocking the iron down with a hammer. To back it up you hit the heel. Bigger planes like jointers have a striking button in front of the throat. Iron planes have an adjustment screw.