Explain the differences between JDK, JRE, and JVM and their roles in Java application development and execution.

JVM (Java Virtual Machine) is a virtual machine responsible for executing Java bytecode. It provides platform independence by interpreting bytecode and managing memory during runtime.

JRE (Java Runtime Environment) includes the JVM and a set of libraries and components necessary to run Java applications. JRE does not contain development tools, only for execution.

JDK (Java Development Kit) is a complete set for Java development. It includes the JRE, compiler (javac), debuggers, and other tools for writing, compiling, and debugging Java programs.

In summary:

• JVM — bytecode execution environment.
• JRE — JVM + standard libraries for running applications.
• JDK — JRE + development tools.

For development, JDK is needed; for running, JRE is sufficient.