an archived web application
an archive file for a web application
an archive (jar file) containing all the files necessary to deploy your Web Service
a structure for deploying a web application
A .war file is a packaged Servlet application. It's just a renamed .jar file of the web-app directory tree. Resin provides a special webapps directory which will automatically expand .war files, configured by the war-dir attribute in the resin.conf's host configuration.