what is the shif gear

Please clarify - "what is shif gear" ------------ A gear shift lever is the mechanical arm (doesn't matter whether column or floor mounted) that, "when the foot brake (and/or clutch if applicable) is applied", allows the operator to "shift" the transmission of a piece of equipment (being tractor, lawn tractor, truck, car, van, crane, fork lift, moving van, etc.) from "P" (Park) or "N" (Neutral) into a gear (Drive, Low, Reverse, etc.) selected by the operator, that allows power from the engine to transfer thru the transmission into the drive axles to provide motion .