The general provisions of laws enacted by Congress are interpreted and implemented by regulations issued by various agencies. These regulations apply the law to daily situations. After regulations are published
in the Federal Register, they
are collected and published in the Code
of Federal Regulations, commonly referred to as the CFR.
The CFR is arranged by subject title and generally parallels the
structure of the United States Code.
Thus, Title 8 of the CFR deals with "Aliens and Nationality",
as does Title 8 of the U.S. Code.