The document discusses the introduction of modularity in Java 9 through the Jigsaw project (JSR-376), highlighting its goals like modularizing the JDK, enhancing security, and providing strong encapsulation. It covers the history of modularity efforts in Java, the differences from OSGi, and outlines how modules work, including the use of service contracts and linking tools. The document also details migration strategies, automatic modules, and promotes resources for further learning about Java 9 modularity.