An unmanned aerial vehicle (UAV), or drone, is an aircraft that operates without an onboard pilot or passengers, either remotely piloted or autonomously. Our research advances UAV technologies across key domains, including post-disaster UAV deployment for restoring communications and supporting rescue operations, swarm UAV communication for coordinated aerial networking, and UAV-based smart farming for precision agriculture and environmental monitoring. We also explore UAV blockchain security for secure data transmission in distributed aerial systems, UAV indoor navigation for autonomous operation in GPS-denied environments, and the integration of UAVs with 5G/6G networks for ultra-reliable, low-latency communication in mission-critical applications.