What is the difference between JDK, JRE, and JVM?

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These three are the layered building blocks of the Java platform. JVM (Java Virtual Machine) — the runtime engine that executes bytecode . It handles classloading, JIT compilation, and garbage collection. Platform-specific, but the bytecode it runs is portable. JRE (Java Runtime Environment) — the JVM plus the standard class libraries needed to run Java programs. No compiler or dev tools. JDK (Java Development Kit) — the JRE plus developer tools ( javac , jar , jdb , javadoc ) needed to build Java programs. Draw the containment relationship: JDK contains JRE which contains JVM. Know specific tools in JDK (javac, jar, jdb). Mention that since Java 11, JRE is no longer distributed separately — only JDK.