Left- and right-hand traffic
The driving side of a road is the side where vehicles must drive. Each country says whether vehicles will drive on the right-hand or left-hand side of the road. This is sometimes called the rule of the road. This basic rule makes traffic move more easily.  It also lowers the risk of head-on collisions. Today about 66.1% of the world's people live in countries that drive on the right-hand side; 33.9% live in countries that  drive on the left-hand side.