What the Grails application directory contains?

When you run command grails create-app,what happened?The answer is it create a lot of directory and file to you.they are the core of a Grails application.Today let me explain what are these folders and files means to you.I make a summary of these stuff as a list:

grails-app:This directory containing core Grails artifacts
+conf: Contains configuration elements,such as DataSource.groovy,UrlMappings.groovy
+controllers :Controllers that handle requests
+domain:Contains domain object class.
+i18n:Contains internationalization message bundles.
+services:Services that encapsulate business logic
+taglib:Dynamic tag libraries
+views:Groovy server page or JSP.
+layouts:the GSP or JSP layouts powered by sitemesh.
grails-test:application unit tests.
hibernate:optional Hibernate configuration.
lib:java lib jar archives
spring:optional Spring configuration.
src:Include other Groovy or Java sources.
+java:Further Java sources for compilation.
+groovy:Further Groovy sources for compilation.
web-app:web application resources (CSS, JavaScript, etc.)