[jboss-as7-dev] JBoss module documentation

Hi, Can someone please point me to the documentation for JBoss module ? I am new to JBoss AS7 and I am looking for some info related to the following topics: - What are the conditions in which we should think of creating a new module ? - Do we need to follow some rules to create the jboss module? Or just by dropping a jar and mentioning the name in module.xml is sufficient? What are the best practices rated to the modules? - How do we create a new module ? Regards, Prashant