What is the purpose of Java Virtual Machine (JVM)?

JVM (Java Virtual Machine) is a virtual machine that allows executing Java bytecode. It abstracts the running program from the hardware of the operating system, ensuring cross-platform compatibility.

Main functions of JVM:

• Loading bytecode: The class loader loads .class files at runtime.
• Verifying bytecode: Checks bytecode for compliance with standards and security.
• Executing bytecode: The JIT compiler (Just-In-Time) converts bytecode into machine code for the current OS and processor architecture, or JVM interprets the bytecode.
• Memory management: The garbage collector automatically frees unused memory.
• Thread management: JVM provides multithreading.

Example architecture of JVM:

+-----------------------+
|       Class loader    |
+-----------------------+
           |
+-----------------------+
|  JVM memory areas     |
|  (Heap, Stack, etc.)  |
+-----------------------+
           |
+-----------------------+
|  Execution subsystem  |
|  (Interpreter, JIT,   |
|     Verifier)        |
+-----------------------+
           |
+-----------------------+
| Interaction with OS  |
+-----------------------+

Thus, JVM is a key component of the Java platform, enabling Java programs to run on any operating system for which a JVM implementation exists.