The JRE is the smallest set of executables and files that constitute the standard java plot form.The Java Runtime Environment (JRE) provides the libraries, the Java Virtual Machine, and other components to run applets and applications written in the Java programming language. In addition, two key deployment technologies are part of the JRE:
Java Plug-in, which enables applets to run in popular browsers; and Java Web Start, which deploys standalone applications over a network.
(a) Java Plug-in : Java Plug-in technology, included as part of the Java Runtime Environment, Standard Edition (Java SE), establishes a connection between popular browsers and the Java platform. This connection enables applets on Web sites to be run within a browser on thedesktop.
(b) Java Web Start : Using Java Web Start technology, standalone Java software applications can be deployed with a single click over the network. Java Web Start ensures the most current version of the application will be deployed, as well as the correct version of the Java Runtime Environment (JRE).