No entry reservation or timed entry. Parking in Grand Canyon Village fills up, so use the free park shuttle buses to reach the main viewpoints.
Backcountry permit early-access lottery: Overnight hikes below the rim start with a two-week lottery that closes on the 1st of the month, 4 months before your trip month (Jan 1 for May trips, Feb 1 for June). Up to 750 winners get a time slot to book. $10 per application.
Phantom Ranch lodging lottery: Cabins and dorms at the canyon bottom are allocated by lottery through the concessioner (Xanterra).
River trips: 12–25 day Lees Ferry trips use a weighted lottery. 2–5 day Diamond Creek trips open 1 year ahead, first-come.
Backcountry permit (overnight hikes): A permit is required for all overnight backcountry use and must be carried by the trip leader. Day hikes below the rim need no permit.