The Parliament of the United Kingdom is the legislature for the UK. It is a bicameral legislature, meaning that it consists of two chambers: the House of Commons and the House of Lords, collectively referred to as the Houses of Parliament. Parliament sits in the Palace of Westminster, in London.
The House of Commons consists of 650 directly elected Members of Parliament (MPs). The House of Lords consists of over 600 appointed peers, known as Lords Temporal, as well as 26 bishops of the Church of England, known as Lords Spiritual. Together, both houses are responsible for introducing, debating and voting on legislation in the form of Acts of Parliament.
As well as the two Houses, Parliament is also made up of a third element: the Crown-in-Parliament. The Crown-in-Parliament (sometimes referred to as the Queen-in-Parliament or the King-in-Parliament) can be said to represent the monarch in its legislative capacity, and reflects the fact that Parliament legislates using the power which was once exercised solely by the monarch.
In order for a Bill to become an Act of Parliament, it is generally required that both Houses vote to pass it. However, the power of the House of Lords to reject or delay legislation is limited by the Parliament Acts. This was done to prevent the House of Lords from obstructing the Commons in pursuing its democratic mandate.
Further changes were made with the passage of the House of Lords Act 1999, which removed all but 92 hereditary peers from the House of Lords.
By constitutional convention, the UK government is comprised of the political party which commands a majority of seats in the House of Commons. For this reason, the UK does not have a strict separation of powers between the legislative and executive branches.
From the majority party, the leader becomes prime minister, and head of the government. The prime minister leads a cabinet of ministers, who are each responsible for different government departments. Constitutionally, ministers are appointed and dismissed by the monarch, but the monarch always does this on the advice of the prime minister.
The House of Lords used to have some judicial functions, in the form of the Lords of Appeal in Ordinary, known as the Law Lords. The Law Lords functioned as the final appeal court. In 2009, the House of Lords lost its judicial functions and the Law Lords were replaced by the Supreme Court.