Primers
Short explainers for the basics the longer posts assume. Read one when a post uses something you haven't met yet.
What a token is, a primer
Tokens in plain English. What a token is and what it is not, opaque versus structured, bearer versus sender-constrained, the JOSE family (JWS, JWE, JWK, JWKS, JWA and JWT) one RFC at a time, where verification keys come from, the JWT best practices, the tokens you will actually meet, and the mistakes that show up in production.
Client credentials, a primer
The OAuth client credentials grant in plain English. The two things the name covers, the one request and one response that make up the flow, the four ways a service proves who it is, what the token says when there's no user in it, why there's no refresh token, and the mistakes that show up in practice.