1. Bills introduced in every Congress are given sequential numbers, e.g., H.R. 1, H.R. 2, S. 1, S. 2, etc.
2. It is also important to know the number of the Congress, e.g., 113th, 112th ,etc.. See Dates of Sessions of the Congress
3. Once a bill becomes law, it gets a public law number in its first printing as a slip law. The public law number has two parts-the first part is the number of the Congress, and the second part indicates it was the nth law passed by that Congress, e.g., Public Law 111-148.
4. The public law is also cited to the Statutes at Large, a second printing of the slip laws, arranged chronologically in bound volumes. A Statutes at Large citation , e.g., 120 Stat. 648, includes the volume and page number on which a law can be found.
5. The public law finally becomes part of the United States Code. This is arranged by subject, so provisions in the public law can be codified in several different titles (subjects.)