This lecture by the instructor covers the importance of Satcom security, focusing on Quantum Key Distribution (QKD) as a method to secure communications. It explains the basics of QKD, its applications in various sectors such as governments, industries, and banks, and why space-based QKD is crucial due to limitations of ground-based fiber infrastructure. The lecture also discusses the current status of QKD research, including successful demonstrations of satellite-to-ground QKD and the development of viable optical ground stations.