Legislation is the term used to describe laws enacted by legislatures, and sometimes also by other bodies with law-making powers such as government departments. It does not include decisions by executive or judicial bodies, nor referendums or ballot initiatives. Nor does it include rules and regulations made by administrative agencies exercising delegated legislative functions, such as school boards, water and sewerage authorities, housing boards or other local governing bodies.

The process for drafting and passing legislation varies from country to country, but is usually based on a constitution which provides the framework for legislation-making. Generally, ideas for policy come from a variety of sources including Senators and their constituents, organisations calling for new policies or old ones to be changed, government agencies or from model laws developed by organisations such as the Uniform Law Commission or Council of State Governments.

Once a bill has been introduced it goes through a number of stages of research, discussion and amendments before it can be passed. In bicameral legislatures, such as the Australian Parliament, the Senate and House of Representatives must pass the same version of a bill for it to become an Act. Disagreements between the two chambers are resolved through procedures such as conference committees.

Once the bill has been passed it is given Royal Assent. This occurs when the Governor-General or the State Governor signs the bill on behalf of the Sovereign (ie the Queen in Australia). After this date the law commences, and it is referred to as an Act of Parliament. The commencement date for a particular piece of legislation is often specified in its text, but can also be found by searching for it on the relevant law database or parliamentary website.