Belts move things. The X and Y motors have sprockets that drive the belts. Most printers also have some way of adjusting the tension on the belts.
Durable and practical.
Designed specifically for linear motion.
GT2 Pulley and GT2 Belt are used together,very convenient to use.
Round tooth profile guarantees that the belt tooth fits smoothly.
Contact with the belt, that minimizes the chance of the belt slipping.