We usually use must to talk about obligations which come from the speaker and we generally use have (got) to when we refer to obligations that come from outside the speaker. …

We use have to / must / should + infinitive to talk about obligation, things that are necessary to do, or to give advice about things that are a good idea to do.

"Must" is a modal verb most commonly used to express certainty. It can also be used to express necessity or strong recommendation, although native speakers prefer the more flexible form "have to."

The modal verb must is commonly used in English to express obligation, necessity, certainty, prohibition, or strong recommendations. It is a versatile word that conveys a sense of importance or certainty in a variety of contexts.

The meaning of MUST is be commanded or requested to. How to use must in a sentence.

MUST definition: to be obliged or bound to by an imperative requirement. See examples of must used in a sentence.

A must is something that's so important it can't be missed or ignored. When you're taking kayaking lessons, a lifejacket is a must.