The United Kingdom is a parliamentary democracy with a constitutional monarch. A king or queen is the head of state, and a prime minister is the head of government. The people vote in elections for Members of Parliament to represent them.
The United Kingdom doesn't have a single, written constitution (a set of rules of government). But this doesn't mean that the UK has an ‘unwritten constitution’. In fact, it is mostly written – but instead of being one formal document, the British constitution is formed from various sources including statute law, case law made by judges, and international treaties. There are also some unwritten sources, including parliamentary conventions and royal prerogatives.
The United Kingdom’s current monarch is Elizabeth II. She is resident in and most directly involved with the UK (her oldest realm), although she is Queen (separately and equally) of 15 other independent states, their overseas territories and dependencies.
The UK is a parliamentary democracy. This means that:
The Constitution of the United States divides the federal government into three branches to ensure a central government in which no individual or group gains too much control: Legislative – Makes laws (Congress), Executive – Carries out laws (President, Vice President, Cabinet), Judicial – Evaluates laws (Supreme Court and other courts). Each branch of government can change acts of the other branches as follows: The President can veto laws passed by Congress. Congress confirms or rejects the President's appointments and can remove the President from office in exceptional circumstances. The Justices of the Supreme Court, who can overturn unconstitutional laws, are appointed by the President and confirmed by the Senate. The U.S. federal government seeks to act in the best interests of its citizens through this system of checks and balances.
Senate – There are two elected Senators per state, totaling 100 Senators. A Senate term is six years and there is no limit to the number of terms an individual can serve. House of Representatives – There are 435 elected Representatives, which are divided among the 50 states in proportion to their total population. There are additional non-voting delegates who represent the District of Columbia and the territories. A Representative serves a two-year term, and there is no limit to the number of terms an individual can serve.
President – The President leads the country. He/she is the head of state, leader of the federal government, and Commander in Chief of the United States Armed Forces. The President serves a four-year term and can be elected no more than two times. Vice President – The Vice President supports the President. If the President is unable to serve, the Vice President becomes President. The Vice President can be elected and serve an unlimited number of four-year terms as Vice President, even under a different president. The Cabinet – Cabinet members serve as advisors to the President. They include the Vice President and the heads of executive departments. Cabinet members are nominated by the President and must be approved by the Senate (with at least 51 votes).
Supreme Court – The Supreme Court is the highest court in the United States. The Justices of the Supreme Court are nominated by the President and must be approved by the Senate. The court is comprised of nine members — a Chief Justice and eight Associate Justices. Currently, there is one Associate Justice vacancy. A minimum or quorum of six justices is required to decide a case. If there is an even number of Justices and a case results in a tie, the lower court's decision stands. There is no fixed term for Justices. They serve until their death, retirement, or removal in exceptional circumstances.