Drivers who wish to operate commercial motor vehicles weighing 26,000 pounds or more, or carrying more than 16 passengers, must have a commercial driver's license in order to do so. These days, these large trucks, also known as "big rigs" or semi-trailer trucks, are very complex and high tech machines that require a high level of knowledge and experience. And while potential commercial driver's license holders must acquire those skills and that knowledge in order to pass the required tests, and they are more easily acquired in truck license classes, those classes are not required. These classes may include information about federal and state commercial driving laws, as well as trip planning and operating a modern semi trailer truck. These classes can cost anywhere from several hundred dollars to $3,500.