People who own or operate aircraft are required to have aircraft licenses. This is no different than only allowing people with valid driver's licenses to operate a motor vehicle. If everyone who wanted to fly any type of aircraft could do so without fulfilling the prerequisites put in place for obtaining aircraft licenses, there would be havoc. Another way in which aircraft licenses can be compared to driver's licenses is through the presence of different classes of licenses. In other words, for most people who sign up to get a driver's license through their local Department of Motor Vehicles, they simply get a passenger car license, which means they are allowed to operate a vehicle for the purpose of moving themselves and other passengers, and light cargo as well, obviously. However, for truck drivers, taxicab drivers, and motorcyclists, special permits and licenses are needed in order to operate their vehicles. For aspiring pilots, the same sort of system is in place. If they want to fly just by themselves or with friends, they will get the equivalent of a passenger license for their aircraft licenses, called the private pilot license. And, for those who want to charge others for the service of flying, they are required to get a commercial aircraft license, which ups the number of hours required and has other stringent requirements. Finally, there is the airline transport license, which is necessary for anyone who would like to be a pilot for a professional airline.