In this chapter, we will give a brief introduction on Domain Specific Languages (DSL) and the issues concerning their implementation, especially in the context of an IDE. The initial part of the chapter is informal: we will sketch the main tasks for implementing a DSL and its integration in an IDE. At the end of the chapter, we will also show you how to install Xtext and will give you a glimpse of what you can do with Xtext. Xtext is an Eclipse framework for the development of DSLs that covers all aspects of a language implementation, including its integration in the Eclipse IDE.