When a person reaches proper driving age and obtains his first driving license, he might be surprised to learn that there are different classes of licenses and that a standard driver's license does not allow for the driving of every vehicle on the road. For individuals who want to drive large trucks like the sort that are used to haul large goods around the country, a special license is required and additional CDL training is also mandatory for anyone who wishes to drive a tractor trailer or other large vehicle for which a Commercial Driver's License would be required.