Auxiliary verbs are used together with a main verb to give grammatical information and therefore add extra meaning to a sentence, which is not given by the main verb.
They are used to form the passive voice.
They are used to form the continuous tense.
They are used to form the perfect tense.
Be, Do and Have are auxiliary verbs, they are irregular verbs and can be used as main verbs. The verbs 'to be' and 'to have' are the most commonly used auxiliary verbs and work alongside the main verbs in any statement.
Modal verbs are also auxiliary verbs, but will be treated separately, these are can, could, may, might, must, shall, should, will, and would, they differ from the others in that they can never function as a main verb.
Be is the most common verb in the English language. It can be used as an auxiliary and a main verb. It is used a lot in its other forms.
Base form = be
Present form = am/is/are
Past form = was/were
Present Participle / Gerund = being
Past Participle = been
More on the Verb To Be
The verb do is one of the most common verbs in English. It can be used as an auxiliary and a main verb. It is often used in questions.
Base form = do
Present form = do/does
Past form = did
Present Participle / Gerund = doing
Past Participle = done
More on the Verb To Do!Note - The auxiliary verb 'do' is always followed by the base form (infinitive).
Have is one of the most common verbs in the English language.
Base form = have
Present form = have / has
Past form = had
Present Participle / Gerund = having
Past Participle = had