The main roles of Parliament are:
debating and approving new national legislation;
scrutinising the work of the Government;
enabling the Government to raise money through taxation;
debating current issues;
protecting the public;
examining proposed European legislation.
A Parliament exists for a maximum of five years after the election of Members of Parliament (MPs) to the House of Commons at a General Election. Any British, Irish or Commonwealth citizen over the age of 18 can stand in a General Election, in which everyone eligible to vote in each constituency selects their new MP by a simple majority vote. The country is divided into over 600 constituencies, each with around 100,000 residents, of which typically 70,000 are of voting age (over 18).
UK politics is based on a party system, where nearly all MPs and some Lords belong to one or other political party. The party with the most MPs forms the Government and the second party forms the Official Opposition. The leader of the main party becomes the Prime Minister. This dates back to the eighteenth century and there have been only two main parties for the past century and more - currently Conservative and Labour.
The main procedure of Parliament consists of debates and divisions. Debates are discussions in the form of motions proposed by an MP and commented on by other MPs, with all speeches going through the Speaker, who is essentially the chair of the meeting of the Commons. At the end of a debate, the Speaker 'puts the question' to find out if the motion is carried or defeated. If needed, MPs may 'divide the House' and a division is held, when MPs file through one of the two lobbies for 'Ayes' (to vote yes) and 'Noes' (to vote no) to the motion.
A new law is created when a parliamentary bill passes through the necessary stages in the Commons and the Lords - including research and consultation, debates in each Chamber and scrutiny by a bill committee - and is approved by the Queen, thus becoming an Act.
The UK has had a two chamber system of government for most of its history: the Upper House (House of Lords) and the Lower House (House of Commons). The two Houses are on the same site - you can tell that you have moved from Commons to Lords as the décor changes from green to red - but they are separate entities. The passing of laws requires the approval of both the Lords and the Commons, as well as the Monarch - the latter these days is only a formality.
The main difference between MPs and Lords is that Lords do not represent constituencies, they are not elected and are not involved in matters of taxation. Lords used to consist of noblemen and churchmen, but since the reform of the Lords in 1999, only 92 hereditary Lords remain and most are life peers appointed by the Government.
Originally meeting wherever the King happened to be, the Commons began to meet in Westminster Abbey in the fourteenth century. After Henry VIII moved out of the Palace of Westminster following a fire, it became the home of Parliament and Government. The Commons began to sit in the Royal Chapel of St Stephen during the reign of Edward VI.
The Palace of Westminster was burned down in the mid nineteenth century and was rebuilt to the current familiar design, including the famous clock tower known as 'Big Ben'. Only the crypt of St Stephen's Chapel and Westminster Hall survived the fire; these are still in use today, with Westminster Hall acting as a second Chamber of the House of Commons. The main Chamber of the Commons was destroyed in a Second World War air raid, but was carefully rebuilt to its former glory after the war.
In the State Opening of Parliament the Queen is driven in state from Buckingham Palace to Westminster, where she sits on the throne in the House of Lords and firstly addresses the Lords - the Upper House - before sending her representative, 'Black Rod', to summon the House of Commons - the Lower House. There is, however, a ritual in which the Commons slams its door in the face of Black Rod to demonstrate its independence from both Monarch and Lords. The door is then only re-opened when Black Rod knocks on the door with his staff of office.
The Queen makes a speech - prepared by the Government - in which details of the business of the next Parliamentary Session are given. A Session of Parliament usually lasts a year from the State Opening November, although it may be cut short by a General Election.
The ceremony of the State Opening of Parliament has many elaborate rituals with their origins in the seventeenth century, although the State Opening itself only dates from the mid nineteenth century. The central part played by the Queen in the State Opening represents the fact that Parliament was originally the advisory council to the Monarch and, indeed, it still formally belongs to the Monarch.
The UK Parliament has its origin in eighth century Anglo-Saxon government, where the 'Witan' was the ad hoc summoning by the King of leading noblemen to provide advice and consent to his laws. William the Conqueror brought in a permanent council of advisers to approve his decisions, which sometimes included other noblemen and churchmen. The extended group of advisers was called the Magnum Concilium (Great Council) and is the forerunner of the House of Lords.
Also of Anglo-Saxon origins were 'Moots' or local shire meetings in which local village representatives, lords and bishops discussed local matters with the sheriff. In Norman times this was known as the 'County Court' and is the forerunner of the House of Commons.
The term 'Parliament' was first used in the thirteenth century and referred to meetings of the King with a group of nobleman and churchmen. These meetings were called as and when the King decided and would take place wherever he was at the time. This followed the signing by King John of the Magna Carta, which instituted legal rights and made the King listen to his noblemen.
Meetings of Parliament gradually became more frequent and records began to be kept in the form of the Rolls of Parliament. Edward I introduced the attendance at Parliament of two representatives from each town, city and county and, by the fourteenth century, Parliament was established as consisting of the Monarch, Lords and Commons, with the Commons now meeting separately from the Lords. Around this time Parliament gradually moved from having the primary task of approving the King's decisions on taxation towards an active role in governing the country. The balance of power between Monarch and Parliament shifted considerably and indeed in 1399 Parliament deposed the King, Richard II.
In the fifteenth century the Commons gained the powers of controlling taxation and making laws. King Henry V acknowledged that both Houses - Commons and Lords - had to approve new laws, which were recorded in the Parliament's own archives from this time. The Lords had become known as 'Peers' and consisted of the 'Lords Spiritual' (bishops and abbots) and the 'Lords Temporal' (by descending rank: dukes, marquesses, earls, viscounts and barons) and this continued to end of the twentieth century, except that abbots were excluded after the dissolution of the monasteries by Henry VIII.