The British parliament is bicameral, consisting of the House of Commons and the House of Lords. Before a Bill can receive the Royal Assent and become law, it must be passed in its final form by both the Commons and the Lords without changes. If one of the Houses makes any change or amendment to it, the other House has to agree to those changes, or make counter-changes of its own (such as reverting to the previous text), in which case it returns to the other House.