CDU/CSU, unofficially the Union parties (German: Unionsparteien) or Union, is the political alliance of the Christian Democratic Union of Germany (CDU) and Christian Social Union in Bavaria (CSU). Both parties share a common parliamentary group in the Bundestag called the CDU/CSU faction (CDU/CSU-Fraktion) or Union faction (Unionsfraktion). The CSU is only organised and contests elections in the German state of Bavaria while the CDU operates in the other 15 states. Both parties are members of the European People's Party and International Democrat Union, and share a common youth organisation, the Young Union.