Rule 302.7 · Creatures

Damage dealt to a creature by a source with neither wither nor infect is marked on that creature (see rule 120.3). If the total damage marked on that creature is greater than or equal to its toughness, that creature has been dealt lethal damage and is destroyed as a state-based action (see rule 704). All damage marked on a creature is removed when it regenerates (see rule 701.19, “Regenerate”) and during the cleanup step (see rule 514.2).