This document discusses drones and their applications. It begins by defining drones as unmanned aerial vehicles that are either remotely controlled or fly autonomously. It then describes the main components of drones and how they work. The document outlines several common types of drones categorized by number of propellers. It provides examples of how drones are used for applications such as mapping, construction, agriculture, mining, monitoring, search and rescue, and science and research. The document also describes an online survey conducted on drone popularity and usage in Hong Kong. It presents the results, which show that drones are not very common but are mostly used for business and leisure. It concludes by discussing further potential developments for drone technology.