An unmanned aerial vehicle (UAV), commonly known as a drone and also referred to as an unpiloted aerial vehicle and a remotely piloted aircraft (RPA) by the International Civil Aviation Organization (ICAO), is an aircraft without a human pilot aboard. ICAO classify unmanned aircraft into two types under Circular 328 AN/190

Autonomous aircraft – currently considered unsuitable for regulation due to legal and liability issues
Remotely piloted aircraft – subject to civil regulation under ICAO and under the relevant national aviation authority
The typical launch and recovery method of an unmanned aircraft is by the function of an automatic system or an external operator on the ground. Historically, UAVs were simple remotely piloted aircraft, but autonomous control is increasingly being employed.not in citation given]. The Nazi-German V-1 flying bomb flew autonomously powered by a pulsejet.

They are usually deployed for military and special operation applications, but also used in a growing number of civil applications, such as policing and firefighting, and nonmilitary security work, such as inspection of power or pipelines. UAVs are often preferred for missions that are too "dull, dirty or dangerous"for manned aircraft.