An optional description tag, not used anywhere by Tomcat, but allowing a way to document the data. Administrative tools that parse the web.xml file, such as web or GUI-based editors, can display this text as help.
When used in <web-app>, provides a longer description for the application.
When used in <servlet>, provides a description of the servlet.
When used in <context-param>, provides a description of the context parameter.
When used in <security-constraint>, provides a description of the security constraint.
When used in <user-data-constraint>, provides a description of the data constraint.