A shift lever is a mechanical component found in vehicles with manual transmissions, such as cars and trucks. It is used to select and engage different gears while driving, allowing the driver to control the speed and power of their vehicle. The shift lever typically has three positions - park, neutral, and drive - but some vehicles may also have additional positions for reverse or other gears. When in park, the car cannot be moved unless it is pushed; when in neutral, the transmission does not transmit power from the engine to the wheels; and when in drive, the vehicle moves forward with power from the engine transmitted through the transmission. By moving the shift lever between these different positions, a driver can control their speed and manage the power of their car or truck.