Drones, known in the professional world as "unmanned aerial vehicles," are gaining increasing importance due to their diverse applications. With the help of these sensor-based aircraft, it is possible to detect and assess building damage, inspect high-voltage masts or chimneys, identify harmful emissions, determine harvest times, or protect properties – all at a fraction of the cost typically associated with such tasks. Law enforcement agencies have also discovered this tool, using it to monitor events, document crime scenes, or track down criminals. This work systematically presents these and many other commercial and governmental applications for the first time, along with a detailed description of the technology required to operate such devices.