five classes · twenty codes you meet every day
Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.
Three sizes in one archive — from a sheet on the fridge to a poster on the wall.
The coloured bar beside each code marks its class. Names are given as they appear in the IANA registry.
A redirect was never meant to change the request method. Browsers changed POST to GET after 301 and 302 anyway, for years, and by the time anyone noticed, half the web depended on it.
So the standard left 301 and 302 alone and added 307 and 308 beside them: same meaning, plus a promise to keep the method.
RFC 9110 says it outright: “for historical reasons, a user agent MAY change the request method from POST to GET”.
Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 4 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.
