A legislative session is the period of time in which a legislature, in both parliamentary and presidential systems, is convened for purpose of lawmaking, usually being one of two or more smaller divisions of the entire time between two elections. A session may last for the full term of the legislature or the term may consist of a number of sessions. These may be of fixed duration, such as a year, or may be determined by the party in power. In some countries, a session of the legislature is brought to an end by an official act of prorogation, in others by a motion to adjourn sine die. In either event, the close of a session generally brings an end to all unpassed bills in the legislature, which would have to be introduced anew to continue debate in the following session.

A bill is a proposal for a new law, or a proposal to significantly change an existing law. A bill does not become law until it is passed by the legislature and has been, in most cases, approved by the executive. Once a bill has been enacted into law by the legislature, it is called an act of the legislature, or a statute. Bills are introduced in the legislature and are discussed, debated and voted upon.