A bill can take months to become law - or just days
All proposed government laws (called bills), except those involving taxation, must be passed in an identical form by the House of Lords as well as the elected House of Commons.
The monarch has the final say on whether a bill becomes law, although this power is rarely used - Queen Anne was the last to do so, in 1707.
Most commonly, the government will propose legislation, possibly via a consultation document called a Green Paper, having outlined its legislative programme in the Queen's Speech during the annual State Opening of Parliament.
Once responses to the paper have been assessed, a modified, firmer proposal called a White Paper is published.
A government bill is then drafted and submitted to Parliament for approval.
The so-called First Reading is just the formal publication of the bill. A Second Reading follows, in which MPs debate the principles in detail before voting.
It's extremely unusual for the government to lose the Commons vote, although it does occasionally happen - most recently with Margaret Thatcher's government's Shops Bill on Sunday trading in 1986.
The Queen outlines the legislative programme set by government
The proposals then go through a committee stage, where a small "standing" committee of MPs, established specifically to consider the bill, wades through it in minute detail, and can vote on proposed amendments.
It returns to the Commons in its modified, report stage, when MPs - sometimes members of the governing party - may propose further amendments.
MPs finally vote on the amended bill at its Third Reading, when it may be approved or rejected but not modified, before the same procedure takes place in parliament's other chamber, the House of Lords.
Further amendments may be made, although it is the Commons that finally approves the bill before it is submitted to the Queen for Royal Assent.
At this stage the bill becomes an Act and is on the Statute Book as a piece of parliamentary legislation until or unless it is amended - via the same process.
The entire procedure normally takes months, although urgent legislation can be passed in days or, in certain circumstances, hours.
In 2004 the government used the Parliament Act to push through legislation banning hunting with dogs.
There is also limited opportunity to propose new laws through private members' bills, where back-bench MPs try to persuade Parliament to adopt causes close to their own hearts - although these rarely result in anything more than publicity for their causes - or private bills, which tend to relate to a specific organisation or corporation.
Parliamentary material is reproduced with the permission of the Controller of HMSO on behalf of Parliament.