This is a book that covers different aspects of UAV technology, including design and development, applications, security and communication, and legal and regulatory challenges. The book is divided into 13 chapters, grouped into four parts. The first part discusses the design and development of UAVs, including ROS customization, structured designs, and intelligent trajectory tracking. The second part explores diverse applications such as search and rescue, monitoring distributed parameter systems, and leveraging drone technology in accounting. The third part focuses on security and communication challenges, including security concerns, multi-UAV systems, and communications security. The final part delves into the legal and regulatory challenges of integrating UAVs into non-segregated airspace. The book serves as a valuable resource for researchers, practitioners, and students in the field of unmanned aerial vehicles, providing a comprehensive understanding of UAV technology and its applications.