Act of Parliament

Acts of Parliament, also called primary legislation, are statutes passed by a parliament (legislature).Act of the Oireachtas is an equivalent term used in the Republic of Ireland where the legislature is commonly known by its Irish name, Oireachtas. It is also comparable to an Act of Congress in the United States.

A draft Act of Parliament is known as a bill.

In territories with a Westminster system, most bills that have any possibility of becoming law are introduced into parliament by the government. This will usually happen following the publication of a "white paper", setting out the issues and the way in which the proposed new law is intended to deal with them. A bill may also be introduced into parliament without formal government backing; this is known as a private member's bill.

In territories with a multicameral parliament, most bills may be first introduced in any chamber. However, certain types of legislation are required, either by constitutional convention or by law, to be introduced into a specific chamber. For example, bills imposing a tax, or involving public expenditure, are introduced into the House of Commons in the United Kingdom, Canada's House of Commons and Ireland's Dáil as a matter of law. Conversely, bills proposed by the Law Commission and consolidation bills traditionally start in the House of Lords.

...
Wikipedia