A different language is a different vision of life.
—Federico Fellini Italian movie director (1920–1993)
A single software language is usually not capable of specifying an application completely. In almost every case, multiple languages are used during the development of a single application. This means that software languages must relate to each other. This chapter describes how software languages can be designed to work together. Part of the content of this chapter was developed in cooperation with Jos Warmer (Ordina, Netherlands).