IntroductionUnderstanding the Java Platform Module SystemFrom Monolithic to Modular: The Evolution of the JDKContinuing the Evolution: Modular JDK in JDK 11 and BeyondImplementing Modular Services with JDK 17JAR Hell Versioning Problem and Jigsaw LayersOpen Services Gateway InitiativeIntroduction to Jdeps, Jlink, Jdeprscan, and JmodConclusion