'Must' or 'have to' in English

This video explains when to use 'must' and when to use 'have to'. We use 'must' to express a necessity or requirement, a strong recommendation or order, or a subjective personal obligation. To express a necessity or requirement, 'must' can be replaced by 'have to'. To express a recommendation or subjective personal obligation, 'must' can be replaced by 'should'. We use 'have to' to express an objective obligation imposed by others, or a responsibility. Unlike 'must', 'have to' can be used in any tense. '