What are FARs & where can I find them? What is FAR 23, 25, 135, etc?
In the US the "Federal Aviation Regulations" (FARs) is shorthand for referring to Title 14 of the Code of Federal Regulations.

You can browse all sections of FARs at ECFR.Gov.

FAR 23, for example, covers airworthiness standards. § 23.25 regulates weight limits.