Driving on the right and on the left
The origins of those rules are based on History and country. Throughout the History people used “keep left” rule. It is only recently that the world has been choosing the “keep right” rule.
The first evidence came from the archaeological time during the Roman Empire. This Empire built many roads through Europe and would have needed to create some rules in order to let people know how interact on the roads.
Some archaeological excavations have showed it was common to drive on the left side of the road at this moment of the History.
Then during the middle ages, Historians could explain the keep left rule by the fact that roads were not always very safe and people on horseback could draw their weapons easily if they met some unsavoury company on the road.
The keep right rule quickly spread throughout the United States and Canada in 18th century. Keeping right on the road was more easily for people and they would gave them a better visibility of traffic.
In Europe this rule started in France, the reasons are not clear at all but whatever the reasons, France switched to the “keep right” system. Under Napoleon Empire, this system has been spread throughout all of the countries which have been conquered.
In England the system has never changed and kept the “keep left” rule that has endured for hundreds of years ago. England was also never conquered by Napoleon.
An official law was made in 1756 in England. In the same time the British Empire was spread throughout the world, this rule expanded too.
Now you know a little bit more about the origin, practice driving on the left hand side of the road before driving in the UK!