The United Kingdom of Great Britain and Northern Ireland is a constitutional monarchy and a parliamentary democracy.
The Queen's title in the United Kingdom is "Elizabeth the Second, by the Grace of God of the United Kingdom of Great Britain and Northern Ireland and of Her other Realms and Territories. Queen, Head of the Commonwealth, Defender of the Faith, etc, etc, etc."
The Queen reigns but does not rule. The United Kingdom is governed by Her Majesty's Government in the name of the Queen. There are still many important acts of government which require the participation of the Queen. The Queen summons, prorogues and dissolves Parliament. Normally she opens the new session with a speech from the throne which outlines her Government's programme. Before a bill which has passed all its stages in both Houses of Parliament becomes a legal entachment it must receive the Royal Assent, which is usually declared to both Houses by their Speakers.
The Queen is the "fountain of justice" and as such can, on the advice of the Home Secretary, pardon or show mercy to those convicted of crimes under English law. The Queen confers peerages, knighthoods and other honours. She makes appointments to many important state offices. She appoints or dismisses Government ministers, judges and members of diplomatic corps. As Commander-in-Chief of the armed services she appoints officers, and as temporal head of the established Church of England she makes appointments to the leading positions in the Church.
The Queen has the power to conclude treaties, to declare war and to make peace, to recognize foreign states and governments, and to annex and cede territory.
An important function of the Queen is the appointment of a Prime Minister. Normally the appointment is automatic since it is a convention of the constitution that the monarch must invite the leader of the party commanding a majority in the House of Commons to form a government. The Queen's closest official contacts are with the Prime Minister (who has an audience of the Queen on average once a week, when the Queen is in London) and, through him, with the Cabinet. She also sees other ministers, generally in order to discuss the affairs of the departments, and sees all the Cabinet papers, the Cabinet agenda in advance, and the minutes of the meetings of the Cabinet and of its committees.
The Queen is the personal symbol of the State and of national unity, and provides a natural focus for popular loyalty and aspiration.
British Parliament is the legislative body in the country. Parliament consists of two houses - the House of Lords and the House of Commons.
The members of the House of Commons are chosen by the electors. There must be a general election every five years, but the Government can order a general election at any time within that period if it so wishes.
The party that has won the general election makes up the majority in the House of Commons, and forms the Government. The party with the next largest number of members in the House, or sometimes a combination of other parties, forms the official Opposition. There are 651 members in the House of Commons (most of them are professional politicians, lawyers, etc.). Members of Parliament (MPs) discuss political problems, make laws. New law is known as a "bill". If the majority of MPs is for the bill, it is sent to the House of Lords for discussion. When the Lords agree, the bill is taken to the Queen for the Royal Assent. The Queen signs, and the Great Seal is fixed. The bill becomes an Act of Parliament.
The House of Lords consists of hereditary and life peers. In the past there used to be a lot of hereditary peers but it has changed and now most people in the House are life peers. They get the title "Lord" or "Lady" for their personal achievements, and their children can't inherit it. Some of them are very competent. For example, famous ex-Prime Minister Margaret Thatcher took her place as Lady Thatcher in the House of Lords in 1992. Full membership of the House of Lords is over 1000.
The main feature of the British political system is "Cabinet Government", that is, the leading role is played not by the Monarch, who remains head of state, or Parliament, which is officially the supreme lawmaking body, but the Cabinet. The Cabinet directs the administration, controls the process of lawmaking, and dominates the House of Commons. It decides what subjects shall be debated in the House, drafts and proposes all important legislation.