the primary form of 'have' is a verb, used when a subject takes ownership or possession of something. It can also be used to talk about an experience, and to form the perfect tense of other verbs when used as a helping verb.
when used as an action verb, 'have' can be conjugated as 'has,' 'had,' or 'having' to show present, past, or progressive tenses. When used as a helping verb, 'have' is used in the perfect tense with another verb to describe a past or completed action. 'Have' can also be used to make the passive, perfect passive, and progressive passive forms of other verbs.
I have a cat.
We are having dinner at 6 o'clock.
We have been working on this project for months.
when using 'have' as the perfect tense, be sure to place it directly in front of the past participle of the verb it’s helping (e.g. 'have gone,' 'have seen,' 'have done'). Be aware of any difference in spelling or pronunciation when conjugating 'have' into present, past, or progressive forms. Lastly, remember that 'have' is always used as an auxiliary verb when forming the passive voice.