A UAV, or unmanned aerial vehicle, is an aircraft operated by onboard computers or remote control. This type of vehicle is also referred to as a drone. UAVs are one of the three major parts of an unmanned aircraft system, which also includes a human controller and systems that allow for communication between the controller and the ground. In recent years, UAVs have expanded from the military to areas like agricultural, scientific, recreational, and commercial activities. Today, this kind of machine may be used to take aerial photographs, deliver packages, spray pest-control chemicals over crops, or even race other drones.