The first part provides a gentle introduction, with examples, to the Java Platform Module System in JDK 9. You will learn the basic concepts of the module system and be introduced to the modules that are built into the Java platform. You will also find out how to develop a module from scratch and how to compile, test, and run it. Second part focuses on developing modules with the Java Platform Module System in JDK 9. Using well-known libraries as examples, you will learn how to develop libraries and applications as modules and will also find out how to migrate existing code to modules. Migration poses many challenges, and in addition to learning about “bottom-up” migration, you will learn about “top-down” migration, where libraries and applications are migrated to modules without waiting for libraries they depend on to migrate first. The third part uses examples from the JDK, to show how to adopt services in your codebase and how to design APIs in a modular fashion. Mark Reinhold is Chief Architect of the Java Platform Group at Oracle. His past contributions to the platform include character-stream readers and writers, reference objects, shutdown hooks, the NIO high-performance I/O APIs, library generification, and service loaders. Mark was the lead engineer for the JDK 1.2 and 5.0 releases, the JCP specification lead for Java SE 6, and both the project and specification lead for JDK 7 (Java SE 7) and JDK 8 (Java SE 8). He currently leads the JDK 9 and Jigsaw projects in the OpenJDK Community, where he also serves on the Governing Board. Mark holds a Ph.D. in computer science from the Massachusetts Institute of Technology. Alan Bateman Consulting Member of Staff in the JDK team in Oracle. I'm currently focused on the Java Platform Module System and the Modular JDK that targets JDK 9. I'm an active member of the OpenJDK project and have a long history in the development of JDK. [BLY-5449]