A controller handles requests and creates or prepares the response and is request-scoped. In other words a new instance is created for each request. A controller can generate the response or delegate to a view. To create a controller simply create a class whose name ends with Controller and place it within the grails-app/controllers directory.

The default URL Mapping setup ensures that the first part of your controller name is mapped to a URI and each action defined within your controller maps to URI within the controller name URI.