In the United States, acts of Congress, such as federal statutes, are published chronologically in the order in which they become law – often by being signed by the President, on an individual basis in official pamphlets called “slip laws“, and are grouped together in official bound book form, also chronologically, as “session laws“. The “session law” publication for Federal statutes is called the United States Statutes at Large. A given act may be a single page or hundreds of pages in length. An act may be classified as either a “Public Law” or a “Private Law”.
Because each Congressional act may contain laws on a variety of topics, many acts, or portions thereof, are also rearranged and published in a topical, subject matter codification by the Office of the Law Revision Counsel. The official codification of Federal statutes is called the United States Code. Generally, only “Public Laws” are codified.
Even in code form, however, many statutes by their nature pertain to more than one topic. Further, portions of some Congressional acts, such as the provisions for the effective dates of amendments to codified laws, are themselves not codified at all. These statutes may be found by referring to the acts as published in “slip law” and “session law” form. However, commercial publications that specialize in legal materials often arrange and print the uncodified statutes with the codes to which they pertain.
In the United States, the individual states, either officially or through private commercial publishers, generally follow the same three-part model for the publication of their own statutes: slip law, session law, and codification.
Rules and regulations that are promulgated by agencies of the Executive Branch of the United States Federal Government are codified as the Code of Federal Regulations. These regulations are authorized by specific enabling legislation passed by the legislative branch, and generally have the same force as statutory law.
This shortened Wikipedia explanation provides a clear overview of the organization of the U.S. Code:
The Code of Laws of the United States of America (variously abbreviated to Code of Laws of the United States, United States Code, U.S. Code, U.S.C., or USC) is the official compilation and codification of the general and permanent federal statutes of the United States. It contains 53 titles (Titles 1–54, excepting Title 53, it being reserved). The main edition is published every six years by the Office of the Law Revision Counsel of the House of Representatives, and cumulative supplements are published annually
The Code is divided into 53 titles which deal with broad, logically organized areas of legislation. Titles may optionally be divided into subtitles, parts, subparts, chapters, and subchapters. All titles have sections (represented by a §), as their basic coherent units, and sections are numbered sequentially across the entire title without regard to the previously-mentioned divisions of titles. Sections are often divided into (from largest to smallest) subsections, paragraphs, subparagraphs, clauses, subclauses, items, and subitems. Congress, by convention, names a particular subdivision of a section according to its largest element. For example, “subsection (c)(3)(B)(iv)” is not a subsection but a clause, namely clause (iv) of subparagraph (B) of paragraph (3) of subsection (c); if the identity of the subsection and paragraph were clear from the context, one would refer to the clause as “subparagraph (B)(iv)”.
Not all titles use the same series of subdivisions above the section level, and they may arrange them in different order. For example, in Title 26 (the tax code), the order of subdivision runs: Title – Subtitle – Chapter – Subchapter – Part – Subpart – Section – Subsection – Paragraph – Subparagraph – Clause – Subclause – Item – Subitem.
The “Section” division is the core organizational component of the Code, and the “Title” division is always the largest division of the Code. Which intermediate levels between Title and Section appear, if any, varies from Title to Title. For example, in Title 38 (Veteran’s Benefits), the order runs Title – Part – Chapter – Subchapter – Section.
According to one legal style manual, a sample citation would be “Privacy Act of 1974, 5 U.S.C. § 552a (2006)”, read aloud as “Title five, United States Code, section five fifty-two A” or simply “five USC five fifty-two A“.
(Read more at Wikipedia: United States Code)
The term “statute” simply refers to a law enacted by a legislative body of a government, whether federal or state.
If you are citing more than one section, use a double-section number (§§), with each of the sections separated by commas.
You can read current and past versions of the U.S. Code in several places: