RFC stands for Request for Comments, and relates to internet governance. This is actually a type of publication that is released by the Internet Engineering Task Force (IETF) and Internet Society (ISOC).
These governing bodies are both concerned with setting standards and overseeing technical development of the internet. RFCs are created by engineers and act as memorandums which describe a range of behaviors, methods, research or innovations that may be relevant to the workings of the internet and related systems. This will then be submitted for peer review, or may be used to convey new concepts and information. It can also occasionally be used for humorous purposes.
The RFC format first appeared in 1969 when it was part of the ARPANET project. It is now the official publication channel for the IETF and Internet Architecture Board. It is used more broadly too by the wider community of computer network researches.
The RFC Code in question is assigned to each RFC in the form of a serial number. Once this number is assigned and published, that RFC will never be altered or redacted in any way. Should the document need amendments, the a new document will be published along with new RFC code.
Some RFCs will therefore supersede others. These are described as deprecated which is a term also used in computer programming to mean defunct or obsolete. The RFC numbers therefore provide a continuous historical record of the evolution of the internet stands and practice.
The process itself is also documented by an RFC with the code 2026. This is The Internet Standards Process, Revision 3. The production process is unique from the standardization process used by other organizations such as ISO. Other experts may submit their Internet Drafts as proposals, with no need for support from external institutions.