Budgeting options include Daily, Weekly or Open at both the Campaign and Ad Set levels. Budgets run from 8AM EST current day and resets at 8AM EST the following day.
Daily: designated daily amount
Weekly: allocate same or unique budget per day of the week; Allotting $0 to a day(s) will pause your campaign/ad set for that day
Open: uncapped spending until funds are depleted for a given campaign/ad set