Usually, Java applications are run in a terminal on Unix systems. This requires a user account to be logged on to the system at all times and a terminal to be open.
There are several drawbacks to this ranging from security, to system performance, to simply having the risk of a user pressing the wrong key on the terminal and killing the Java application.
The Java Service Wrapper addresses these issues by making it possible to install your Java application as a daemon. It offers automatic detection of the service management tools (also known as init systems) available on your OS, or lets you configure a specific system to use when launching your application as a daemon.
Are you using Windows? Please check our QNA for Windows.