The Westminster system, or Westminster model, is a type of parliamentary government found in, and elsewhere derived from, the Parliament of the United Kingdom. Key aspects of the system include an executive branch made up of members of the legislature which is responsible to the legislature, the presence of parliamentary opposition parties, and a ceremonial head of state who is separate from the head of government. The term derives from the Palace of Westminster, the seat of the British parliament. The Westminster system can be contrasted with the presidential system, which originated in the United States, and with the semi-presidential system based on the government of France.