A Web application is a group of HTML pages, JSP pages, servlets, resources
and source file, which can be managed as a single unit. A Web archive (WAR)
file is a packaged Web application. WAR files can be used to import a Web
application into a Web server.
In addition to project resources, the WAR file includes a Web deployment
descriptor file. The Web deployment descriptor is an XML file that contains
deployment information, MIME types, session configuration details, and other
settings for a Web application. The Web deployment descriptor file (web.xml)
provides information about the WAR file is shared with the developers, assemblers,
and deployers in a Java EE environment.
The Web development environment provides facilities for importing and exporting
WAR files, using the following wizards:
Import Resources from a WAR File, which requires that you to
specify a Web project. You can use existing projects or create them as you
use the wizard.
Export Resources to a WAR File, which requires only an export
location and some optional settings