Grails ships with a few convenience targets such as
create-controller,
create-domain-class and so on that will create
Controllers and different artefact types for you.
These are merely for your convenience and you can just as easily use an IDE or your favourite text editor.
For example to create the basis of an application you typically need a
domain model:
grails create-domain-class book
This will result in the creation of a domain class at
grails-app/domain/Book.groovy
such as:
There are many such
create-*
commands that can be explored in the command line reference guide.