A credential is a pass that proves something about the person carrying it: who they are, that their membership is current, that they are entitled to a member price or a staff benefit. It is the same wallet pass technology as a loyalty card, put to a different purpose. A loyalty pass carries state that is pleasant to lose track of; a credential carries an entitlement that someone will act on, so the questions that matter are issuance, freshness and revocation rather than points and stamps.
Membership is the usual case. A gym membership checked at the turnstile, a resident pass for a club, a season ticket for a gate, a staff pass that unlocks employee pricing: each is issued to a named person, checked at a reader or a till, and expected to stop working the moment the entitlement ends. Physical credentials are bad at that last part. A plastic card keeps working until it is collected, and an RFID fob authenticates whoever is holding it, which is why lending is the default failure mode of every membership that is worth borrowing.
A wallet credential closes both gaps. Account binding ties the pass to the member's own account, so presenting it means their device is at the reader rather than someone else's copy, and the encrypted payload of an NFC tap is not something a screenshot reproduces. Because the pass stays connected to the issuer, a push update can change what it says in seconds: a new tier, extended validity, a revoked credential that no longer validates anywhere. Nobody has to be found and asked for their card back.
Not every pass is a credential, and it is worth being deliberate about which are. A coupon or a gift card is often meant to move between people, so binding it would break the point. A credential is the opposite: personal, verified, and only as good as the system's ability to withdraw it.