In Great Britain, roads are given a letter with 1-4 numbers after it. This is how they are named. The letter is the category of the road. There are two main types of categories: motorways (with the letter "M") and non-motorways. There are two types of non-motorways: A roads (with the letter "A") and B roads (with the letter "B"). A roads are more important than B roads. There are also a very small number of C roads.