A gearshift is the lever or mechanism in a vehicle that lets the driver change gears. When you shift gears, you're adjusting how the engine's power connects to the wheels, which changes how fast the vehicle can go and how much force it can deliver.

In a car with a manual transmission, the gearshift is a stick that the driver moves to different positions: first gear for starting from a stop, second and third for gradually building speed, and higher gears for highway driving. Each gear is designed for a different speed range. Starting in fifth gear would be like trying to pedal a bicycle that's in its highest gear: the engine would struggle just as your legs would.

In a car with an automatic transmission, the gearshift is simpler, usually offering just Park, Reverse, Neutral, and Drive, because the car handles most gear changes itself.

Motorcycles and bicycles also have gearshifts. On a bicycle, you might shift to a lower gear when climbing a steep hill (making pedaling easier but slower) and a higher gear when racing downhill (making each pedal push move you farther).