An Act of Parliament is a decree proclaiming the law, passed by the legislature and given royal assent by the Crown.  Acts are also known as Statutes.

Legislation also includes Delegated Legislation which is Legislation made by a person or body other than Parliament, under authority granted to that person or body by an Act of Parliament. Individually, Delegated Legislation can come in various forms such as 'Regulations', 'By-laws', 'Rules', 'Ordinances', and 'Orders-in-council'. Collectively, they are variously referred to as 'Subordinate Legislation', 'Statutory Rules', 'Legislative Instruments', 'Statutory Instruments', or 'Subsidiary Legislation'. For more information on Delegated Legislation please see the Delegated Legislation tab.

When Acts are passed, they are given a sequential number for that year. They are published in pamphlet form with the title, number and year on the cover. When passed in this way, they are known as Numbered Acts, or Sessional Acts. For Example: Extradition Act 1988 (No. 4 of 1988).

Acts are either:

• Principal Acts (also known as Original Acts) - which represent new Legislation.
• Amending Acts - which are Acts designed to update or amend existing Acts. Amending Acts may have the same or a similar name to the Act which they modify, often with the word "amendment" in the title. This usually does not apply when an Amending Act updates many existing Acts.

For example:
the Crimes and Other Legislation Amendment Act (Cth) (No 20 of 1997)
amends one section of
the Extradition Act 1988 (Cth) (No 4 of 1988).

In this example, the first act is the Amending Act, and the Extradition Act is the Principal or original Act. Both Acts are issued in the numbered series.

Acts are available in three forms: