There are some pretty advanced drones out there, but you might not even be able to spot them.
Asked by: Tom Fisher, Leeds
Drones are radio-controlled flying gadgets with several propellers that may be used for filming, racing, and in the future perhaps even widespread delivery of parcels.
Military drones resemble small aircraft with no pilots. Some can take off, fly and land by themselves. They can perform surveillance over enemy territory or even deploy missiles to attack specific targets in dangerous places where we may not want to risk human pilots.
One of the most advanced today is the Taranis, a UK-built drone with a top speed of 1,127km/h (700mph) and 9.7m wingspan that is nearly invisible to radar.