default-web.xml is a global web deployment descriptor file that is shared by deployed web applications. It is used to configure the DefaultServlet and JspServlet servlets. In addition, it specifies: MIME mappings based on extensions Welcome files Global filters and security constraints Individual web applications inherit and might override the configuration settings inherited from default-web.xml with their own web.xml. The default-web.xml for each server instance is shared by all web applications deployed on the server instance. Depending on the configuration capabilities of the hosting application, a virtual server might replace the server-wide default-web.xml with its own. In that case, a virtual server's default-web.xml is shared by all web application deployed on the virtual server.