The Java Runtime Environment (JRE) is a software package that provides the necessary components to run Java applications. It includes the Java Virtual Machine (JVM), core libraries, and other files that support the execution of Java programs. The JRE allows developers to create applications that can run on any device with a compatible JRE installed, promoting cross-platform functionality. The JRE is part of the larger Java Development Kit (JDK), which includes tools for developing Java applications. While the JDK is used for writing and compiling Java code, the JRE is specifically designed for running it. This separation allows users to run Java applications without needing the full development environment.