render

// renders text to response
render "some text"
// renders text for a specified content-type/encoding
render(text:"<xml>some xml</xml>",contentType:"text/xml",encoding:"UTF-8")
// render a template to the response for the specified model
render(template:"book",model:[book:new Book(title:'The Shining',author:'Stephen King')])
// render each item in the collection using the specified template
render(template:"book",collection:[b1, b2, b3])
// render a template to the response for the specified bean
render(template:"book",bean:new Book(title:'The Shining',author:'Stephen King'))
// render the view with the specified model
render(view:"viewName",model:[book:new Book(author:'Stephen King')])
// render the view with the controller as the model
render(view:"viewName")
// render some markup to the response
render {
    div(id:"myDiv", "some text inside the div")
}
// render some XML markup to the response
render(contentType:"text/xml") {
    books {
         for(b in books) {
            book(title:b.title,author:b.author)
         }
    }
}
// render a JSON ( http://www.json.org ) response with the builder attribute:
render(contentType:"text/json") {
	book(title:b.title,author:b.author)
}
// Automatic marshalling of XML and JSON
import grails.converters.*
…
render Book.list(params) as JSON
render Book.get(params.id) as XML