Each United States jurisdiction (United States, each state) has a constitution, session laws and a code.
Session laws are the laws of a jurisdiction collected in chronological order. Individual U.S. laws are called Public Laws (e.g. Public Law 111-002) and individual Illinois laws are called Public Acts (e.g. Public Act 96-0073). The session laws of other states have different titles. Consult The Bluebook for more information.
A code is a subject organization of all the laws currently in force in a jurisdiction. The code of the United States is called the United States Code. The code of Illinois is called the Illinois Compiled Statutes.
This section on Statutory Research has 3 subtabs: Constitutions, Federal Statutory Law and State Statutory Law: Illinois.