In-vehicle electronic embedded systems are realized through complex distributed architectures. They have to provide a level of quality of service fixed by the market, the safety requirements, the cost requirements. Therefore their development and their production have to be based on a suitable methodology including their modelling, validation, optimisation and test. In this chapter, we identify the main characteristics of such systems. We introduce an ADL (Architecture Description Language), termed EAST-ADL that supports their description at each step of the development process. Finally, we present how to prove some properties on a suited model of an operational architecture described in this language.