How does a manual transmission in a car work?

There are two shafts which run through the gearbox, the input shaft and the output shaft, and the two are connect by pairs of gearwheels, one for every 'gear' of the car. They are paired together: Gear 1 will have a small wheel on the input shaft and a large wheel on the output shaft, meaning less speed and more turning force. Gear 5 will have a large wheel on the input shaft and a small wheel on the output shaft, to ensure a high speed.

Moving the gear stick to select a gear pulls a 'synchromesh' into place. This locks the input shaft a gear on the input shaft, allowing the movement to be transferred to the output shaft via that particular 'gear'. In the Neutral setting, the synchromeshes are all disengaged. In Reverse gear, there are three wheels involved in the transmission, instead of two.