The Java 2 Runtime Environment (J2RE) is a software package that provides the necessary libraries and components to run Java applications. It includes the Java Virtual Machine (JVM), which allows Java programs to execute on any device that has the J2RE installed, ensuring compatibility across different operating systems. J2RE is part of the larger Java 2 Platform, which also includes the Java Development Kit (JDK) for developers. While the JDK is used for creating Java applications, the J2RE is specifically designed for users who only need to run those applications. This separation helps streamline the experience for both developers and end-users.