A Java Virtual Machine (JVM) is an abstract computing machine that enables a computer to run Java programs. It interprets compiled Java bytecode, allowing developers to write code once and run it on any device that has a JVM, promoting platform independence. The JVM also manages system resources, including memory and execution threads, ensuring efficient program execution. It includes features like garbage collection, which automatically reclaims memory, and just-in-time (JIT) compilation, which improves performance by converting bytecode into native machine code during runtime.