The house of commons is made up of 650 elected MPs.
MPs represent a particular political party, or stand as independant candidates.
The Government is the party in the House of commons who are in power at the time, the party in power is the one who won majority votes at the last election.
They are the most powerful part of parliament - created the Parliaments Act 1991 and 1949 which state that they do not need agreement of the Lords to pass legislation.