The Internet of Drones (IoD) refers to a network of interconnected drones, also known as Unmanned Aerial Vehicles (UAV), communicating with each other and other devices over the Internet. IoD facilitates various applications and services by facilitating data exchange, coordination, and management among drones, as well as with ground control stations or cloud-based platforms. The increasing number of UAVs in airspace requires an increased focus of UAV security to mitigate future risks, including unauthorized access, data breaches, and malicious attacks. Authentication and access control are crucial in addressing security concerns within the IoD ecosystem. Authentication verifies the identity of drones, while Access control mechanisms prevent unauthorized access to resources and enable authorized users to access resources appropriately. This chapter begins by exploring the fundamentals of access control and discussing its need in the IoD systems. It emphasizes the importance of access control in protecting IoD systems, addressing both security and privacy concerns. The chapter then looks into various traditional and dynamic access control mechanisms. It further explores technologies enabling dynamic access control, along with case studies and applications to illustrate real-world implementations, and finally leading to conclusions that summarize major findings and indicates the importance of dynamic access control for securing the IoD systems.