Grails is an open-source, rapid web application development framework that provides a super-productive full-stack programming model based on the Groovy scripting language and built on top of Spring, Hibernate, and other standard Java frameworks. Ruby on Rails pioneered the innovative coupling of a powerful programming language and an opinionated framework that favors sensible defaults over complex configuration, but many organizations aren't yet ready to stray from the safety of Java or forgo their current Java investments. Grails makes it possible to achieve equivalent productivity in a Java-centric environment. Over the course of this book, the reader will explore the various aspects of Grails and also experience Grails by building a Grails app.