United States federal law is codified in the United States Code. The Code is arranged as 54 titles of various subject matters of federal jurisdiction (e.g. Title 12: Banks and banking; Title 17: Copyrights; Title 47: Telecommunications).
The titles are then split up into chapters, which are further divided into sections (e.g. Title 17: Copyrights -- Chapter 1: Subject matter and scope of copyright -- Section 106: Exclusive rights in copyrighted works).
Federal laws might be cited as follows: TITLE U.S.C. § SECTION. For example, 47 U.S.C. § 21 refers to Telecommunications (Title 47), Submarine cables; willful injury to; punishment (section 21).
The U.S. Code can be found at many locations on the Internet:
Westlaw provides an annotated U.S. Code, which includes interpretations and clarifications made by the courts, the history of the statute, and analysis in secondary sources such as encyclopedias and law review articles.
Federal laws are often known by their "popular name" or "short title" rather than by their U.S. Code title and section. Popular name tables exist to allow researchers to match the popular name with the location in the code.