See Fair Work Act 2009 s.172(1)
An enterprise agreement is an agreement made at the enterprise level that contains terms and conditions of employment, including wages, for a period of up to 4 years from the date of approval.
Whilst an enterprise agreement must have a nominal expiry date within 4 years, under the legislation the agreement will continue to operate after that date until it is replaced by a new enterprise agreement or terminated by the Fair Work Commission.
The Fair Work Act sets out requirements for bargaining for a proposed enterprise agreement.
This term describes an agreement that is proposed to be negotiated, or is being negotiated, with a view to it being approved by the Commission as an enterprise agreement. A series of claims on behalf of a group of employees whose bargaining representatives seek to negotiate with the employer could be a proposed enterprise agreement for the purposes of the Fair Work Act.
There are 2 main types of enterprise agreements that can be made under the Fair Work Act:
 Explanatory memorandum to Fair Work Bill 2008 at para. 643; See also discussion in Wesfarmers Premier Coal Ltd v Automotive, Food, Metals, Engineering, Printing and Kindred Industries Union (No 2)  FCA 1737 at paras 55–56; [(2004) 138 IR 362].