Unmanned aerial vehicle.

From the Wikipedia page:

An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot on board. Its flight is either controlled autonomously by computers in the vehicle, or under the remote control of a navigator, or pilot (in military UAVs called a Combat Systems Officer on UCAVs) on the ground or in another vehicle.

There are a wide variety of drone shapes, sizes, configurations, and characteristics. Historically, UAVs were simple remotely piloted aircraft, but autonomous control is increasingly being employed.

They are predominantly deployed for military applications, but also used in a small but growing number of civil applications, such as firefighting and nonmilitary security work, such as surveillance of pipelines. UAVs are often preferred for missions that are too 'dull, dirty, or dangerous' for manned aircraft.

Note that:

• Questions about Autonomous underwater vehicles should use the auv tag.
• Questions about autonomous Unmanned ground vehicles should use the ugv tag.
• The drone tag should only be used for questions about autonomous drones which don't fit into the auv, uav or ugv tags.
• Questions about remotely controlled UAVs are probably off topic on Robotics and are more likely to be suitable over on Electrical Engineering Stack Exchange.