A Private JVM is a non shared environment in which you have full control over. This gives you the flexibilty to restart your own JRUN Server without interfering with other running JRUN Servers. It is when you have your own servlet engine installed into your home directory and its dedicated to you and only you. This is great for serious developers that need the FULL control over the configuration files, start and restarting the engine, and much more. Its just like you were developing on your local server.