An unmanned aerial vehicle (UAV) or unmanned aircraft system (UAS),
commonly known as a drone, is an aircraft with no human pilot, crew,or
passengers on board, but rather is controlled remotely or is autonomous.
UAVs were originally developed through the twentieth century for
military missions too dangerous for humans, and by the twenty-first had
become essential assets to most militaries. As control technologies
improved and costs fell, their use expanded to many non-military
applications.These include aerial photography, area coverage, precision
agriculture, forest fire monitoring,river monitoring, environmental
monitoring, weather observation, policing and surveillance,
infrastructure inspections, smuggling, product deliveries,
entertainment, and drone racing.