A Java EE application is packaged into one or more standard units for
deployment to any Java EE platform-compliant system. Each unit contains
A functional component or components, such as an enterprise bean, web
page, servlet, or applet
An optional deployment descriptor that describes its content
Once a Java EE unit has been produced, it is ready to be deployed.
Deployment typically involves using a platform’s deployment tool to
specify location-specific information, such as a list of local users who
can access it and the name of the local database. Once deployed on a
local platform, the application is ready to run.