RFCs or Request for Comments, is the way that the internet develops standards. Read this to learn more: https://www.lifewire.com/what-is-internet-request-for-comments-rfc-4092366
Now the important thing is how to read an RFC.
- From the organization that approves RFCs. https://www.ietf.org/blog/how-read-rfc/
- This is short and sweet but applies to just about any technical document: https://softwareengineering.stackexchange.com/questions/179022/how-does-one-read-rfcs-and-similar-documents
Skim the HTTP RFC to answer a few questions: https://www.rfc-editor.org/rfc/rfc7231.txt
Is this an official RFC? What RFC did it update?
- What does this RFC give guidance on how to do?
- What are the 5 families of response status codes?
- What is a GET request and what does it look like?
- What is a User-Agent?
- What RFC guides "cache-control" in a header?