306.5 Loyalty is a characteristic only planeswalkers have.
306.5a
The loyalty of a planeswalker card not on the battlefield is equal to the number printed in its lower right corner.
306.5b
A planeswalker has the intrinsic ability “This permanent enters with a number of loyalty counters on it equal to its printed loyalty number.” This ability creates a replacement effect (see rule 614.1c).
(refs: 614.1c)
306.5c
The loyalty of a planeswalker on the battlefield is equal to the number of loyalty counters on it.
306.5d
Each planeswalker has a number of loyalty abilities, which are activated abilities with loyalty symbols in their costs. Loyalty abilities follow special rules: A player may activate a loyalty ability of a permanent they control any time they have priority and the stack is empty during a main phase of their turn, but only if none of that permanent’s loyalty abilities have been activated that turn. See rule 606, “Loyalty Abilities.”
(refs: 606)