OAuth
A standard for granting an application limited access to your data in another service without giving it your password.
When an app asks to read your calendar and you approve, that is OAuth. A scoped token is issued rather than a credential, and it can be revoked without changing your password.
Consent phishing abuses this directly: a malicious application requests broad permissions, the user approves without reading, and the attacker retains access to mail and files even after a password reset. Restricting who can consent to applications is the control that matters.
Where this comes up
OAuth sits inside our identity and access work. If you are trying to work out what this means for your own environment rather than in the abstract, that is the page worth reading next, and a short call will get you a straight answer faster than either.