The Ten Word Review

Wikipedia says…

Right-hand traffic and left-hand traffic mean regulations requiring all traffic to keep either to the left or the right side of the road. This is so fundamental to transport that it is sometimes referred to as the rule of the road. The purpose of this basic rule is to facilitate traffic flow and reduce the likelihood of head-on collisions. Though originally most traffic drove on the left worldwide, today right-hand traffic prevails. About 34% of the world's people live in left-traffic countries and 66% in right-traffic countries; roughly 28% of the world's total road distance carries traffic on the left, and 72% on the right.