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 (Union fraktion). The CSU is only organised and contests elections in the German state of Bavaria while the CDU operates in the other 15 states.