<p>The utilization of Unmanned Aerial Vehicles (UAVs) in contemporary times is not limited to military or emergency applications. UAVs are present in every aspect of transportation or movement including medicine delivery, general consumable delivery, warfare, reconnaissance and multiple other areas. Each of these applications require UAVs to cater to the particular mission. The design procedure involved in the same is tiring, vast and requires a high level of mathematical, mechanical and computational knowledge. This study provides a holistic view of all the design requirements for a UAV in an analytical and computational perspective. A brief description on the systems, working conditions and applications of UAVs and Unmanned Aerial Systems (UAS) is provided. Further, this study, by scrutinizing available scientific data, describes all the important procedure involved. This includes the design procedure and relevant calculations, and computational methodologies such as control dynamics and computational fluid dynamics. The various loading conditions are also discussed based on the complexity of the mission. The design and simulation procedure is provided for different types of UAVs including multirotor, fixed- wing models and hybrid models. In addition to the same, the applications of the UAS in various fields is also described. Hence, this study presents the entire design and operational condition simulation procedure used for UAS by combining the data collected from the available scientific procedures and articles.</p>