Many countries permit both types of vehicles on their roads.
Terminological confusion may arise from the terms left-hand drive or right-hand drive to indicate the side of the road along which vehicles are driven.
All vehicular traffic proceeding in the same direction on any road shall keep to the same side of the road, which shall be uniform in each country for all roads.
Domestic regulations concerning one-way traffic shall not be affected.
In the past, several countries have had different rules in different parts of the country (e.g., Canada until the 1920s, Spain, Brazil and others).
Currently, China, the United States and the United Kingdom each have territories that do not follow the major country's primary traffic rule.
In China (which has not ratified the Convention), drivers drive on the right, while in the special administrative regions of Hong Kong and Macau they drive on the left.
In the United States, driving is on the right, while traffic in the US Virgin Islands, as on many Caribbean islands, drives on the left.The United Kingdom drives on the left, but its overseas territories of Gibraltar and British Indian Ocean Territory drive on the right.Most other countries not parties to the Convention still follow the practice.The terms right-hand traffic and left-hand traffic refer to regulations requiring all bidirectional traffic, unless otherwise directed, to keep to the right or to the left side of the road, respectively.With a few minor exceptions, each country specifies a uniform road traffic flow: left-hand traffic (LHT), in which traffic keeps to the left side of the road, or right-hand traffic (RHT), in which traffic keeps to the right.The terms nearside (or kerbside) and offside (or off-kerb side) are used in some English-speaking countries to refer to the passenger and driver sides (in modern parlance) of a vehicle: the "nearside" is closest to the kerb (in the designated direction of traffic) and the "offside" is closest to the centre of the road.