The House of Commons is the most powerful of Parliament's two houses.
In the 2005 General Election, 646 members, or MPs, were voted in by the public.
The group, or political party, with the most MPs is allowed to form a team of people who run the country - called a government.
The Commons is the most important place for discussing policies and making laws.
There are only 427 green leather seats so when it's full a lot of politicians have to stand!