1) A belt drive transfers rotary motion between two shafts using one or more continuous belts looped over a pulley on each shaft. Belts come in various types like flat, round, V-shaped, and toothed belts for different applications. 2) Common belt drive arrangements include open drives with parallel shafts rotating in the same direction, crossed drives with parallel shafts rotating in opposite directions, and compound drives using multiple pulleys. Idler pulleys are also used to adjust tension and increase contact area. 3) Belt drives are used widely in machinery and vehicles to transmit power economically over varying distances and speeds depending on the belt and pulley type.