A bill is a proposal for a new law, or a proposal to change an existing law that is presented for debate before Parliament. Bills are introduced in either the House of Commons or House of Lords for examination, discussion, and amendment. When both Houses have agreed on the content of a bill it is presented to the reigning monarch for approval (known as Royal Assent). After Royal Assent is given a bill becomes an Act of Parliament and is law. A UK public bill is a bill that has a general effect in some or all the constituent parts of the UK.