The UK Parliament

The development of Parliament over one thousand years, from the Anglo-Saxon Witan to the reign of Elizabeth I.Parliament examines what the Government is doing, makes new laws, holds the power to set taxes and debates the issues of the day. The House of Commons and House of Lords each play an important role in Parliament's work.The business of Parliament takes place in two Houses: the House of Commons and the House of Lords. Their work is similar: making laws (legislation), checking the work of the government (scrutiny), and debating current issues. The House of Commons is also responsible for granting money to the government through approving Bills that raise taxes. Generally, the decisions made in one House have to be approved by the other. In this way the two-chamber system acts as a check and balance for both Houses.

There are two Houses of Parliament:The Houses Lords are much power than the Houses of Commons.Therefore the House of Commons was originally far less powerful than the House of Lords. There are 659 constituencies in the UK: 529 in England, 72 on Scotland, 40 in Wales and 18 in Northern Ireland. Constituens are different geographical size,some very lagre ,some covered small area. Prime Minister is elected through general elections.The system called  the’first past the post ‘is the person who has the most votes wins,even if they have only one vote more than the next person.
http://www.parliament.uk/about/how/role/system/