have to
fixed phrase.you use this to say that something is necessary or that you are forced to do it.
fixed phrase.a semi-modal auxiliary used to express objective obligation or necessity. Unlike 'must', it is frequently used for obligations imposed by external rules or circumstances.
“I have to go to work now.”
“In this country, you have to drive on the left side of the road.”
“The committee members have to reach a unanimous decision before the fiscal year concludes to secure the necessary funding.”
the 'to' is followed by the base form of a verb.
contrast with 'must' for internal vs. external obligation; 'have to' is much more common in spoken English and can be used in all tenses.
learners often confuse 'must' and 'have to', incorrectly adding 'to' after 'must'.