This course accompanies Jonathan Levin's highly praised trilogy, '*OS Internals,' with deeper discussions and hands-on examples. It focuses on macOS Monterey (10.17), Ventura (10.18), and iOS versions 15 and 16, covering significant changes in these later versions. The course explores Apple's operating systems from a reverse engineer’s perspective, offering in-depth coverage of both documented and undocumented features, tools, and updates. The content is taught by the author himself and presents an opportunity to master reverse engineering techniques for macOS and iOS.