Access control is a critical aspect of developing secure and scalable software, and it is best addressed early in the development process, as retrofitting can lead to complex issues. This discussion focuses on four key types of access control: entitlements, permissions, roles, and feature flags, explaining their differences, usage, and interrelations. Entitlements are linked to billing plans and define what features a user can access, permissions dictate specific user actions, roles group these permissions for easier management, and feature flags allow temporary or conditional feature access. The text also highlights how the Kinde platform simplifies implementing these controls, using practical examples that demonstrate the seamless integration of entitlements, permissions, roles, and feature flags to enhance application security and functionality.