The applications of the Unmanned Aerial Vehicles (UAVs) in challenging fields such as military, defense, civil, and agriculture have made them a promising futuristic technology. The futuristic UAVs using the 5G and beyond 5G technology with more sophisticated and intelligent algorithms require a framework for their optimization and troubleshooting. This has invited the researchers to come out with the advanced concept of digital twin for the UAVs. Digital twin enabled UAVs provide a framework for the optimization, training, and testing of the intelligent algorithms using the real-time data from the drone operations. In this chapter, an overview and investigation into the research work related to the digital-twin enabled UAVs has been provided with some higher level insights. Digital twin enabled UAVs architecture has been discussed with its physical and virtual layers. Different applications of the UAVs with their major remote sensing monitoring role have been investigated in more detail. Various case studies of the UAVs employing the digital twins for online learning and optimization are also discussed. Open issues, challenges, and future research directions related to the working of the digital twin enabled UAVs have also been highlighted.