What is a "production account" as it applies to the just-announced rate limits?

I just got the notifications about rate limits for non-production accounts.

What exactly is a “production account”? I can’t find a definition anywhere.

Yeah I was under the impression that I was using a “production account”, but I got the email. I don’t remember having to choose between prod and non-prod.

OK - just got another email indicating that they meant that the rate limits would apply for free accounts.

Yeah I was under the impression that I was using a “production account”, but I got the email. I don’t remember having to choose between prod and non-prod.