U.S. federal laws are passed by both houses of Congress, and then signed into law by the President. These laws are first issued as "slip laws" and are referred to as Public Laws (for example the Antiterrorism and Effective Death Penalty Act of 1996 is Public Law 104-132, or P.L. 104-132. These Public Laws are sequantially numbered, first with the number of the Congress, then by the number of the law itself.
Several months later these laws are published in the permanent set called United States Statutes at Large. Eventually these laws are "codified", or placed into their appropriate place within the 50 titles of the United States Code.
Tracking congressional activity is a complex task, but the easiest way to do this is with Congress.gov. This freely-available tool allows you to browse or search for bills at any stage of the legislative process. Search defaults to the current Congress, but the database goes back to previous sessions of Congress.
Public laws are also known as "slip laws" because of their initial publication in individual slip format.
Public laws are bound together into the United States Statutes at Large, a sequential publication of laws in the order they were signed into law.
The statutes are the law "as passed", but the compilations are the codification of the law into the United States Code, the law "as amended."
By far (in my opinion) the easiest way to navigate the U.S. Code is to use the version published by the House Office of the Law Revision Counsel (https://uscode.house.gov/). Some of its helpful features include:
