JRE

The Java Runtime Environment (JRE) is a software package that provides the minimum requirements for executing Java applications. It includes the Java Virtual Machine (JVM), the Java Class Library, and other components needed to run Java programs. The JRE does not include development tools such as a compiler or debugger; those are provided by the Java Development Kit (JDK).

The JRE enables platform independence by running Java bytecode that has been compiled from source code. The JVM interprets or compiles bytecode at runtime, manages memory, and enforces security and access controls. The core class libraries provide the standard Java API for tasks such as input/output, networking, data structures, and user interfaces. Historically, the JRE also included a browser plug-in for running Java applets, but applets have largely fallen out of use and support has waned in modern browsers.

Distribution and versions: The JRE is part of the Java Platform, Standard Edition (Java SE). Oracle and other vendors distribute JRE builds in various packaging formats; Oracle's distribution has evolved in licensing and may be offered as a standalone runtime or as part of the JDK. OpenJRE is the open-source implementation used by many non-Oracle builds, and numerous operating systems provide their own JRE/JDK packages. Java SE updates deliver security and performance fixes, and users typically install the latest supported JRE to run Java applications.