Just-In-Time (JIT) compilation is a crucial feature of the Java Runtime Environment that enhances the performance of Java applications during execution. Unlike traditional compilation, which occurs before program execution, JIT compilation takes place at runtime. It converts Java bytecode into native machine code, allowing the Java Virtual Machine (JVM) to execute methods more efficiently. This process is triggered when a method is called, enabling the JVM to optimize frequently used methods for better performance. By compiling code “just in time,” JIT compilation helps bridge the performance gap between Java applications and native applications, making Java more competitive in speed and efficiency.