French Auxiliary Verbs

An auxiliary verb, also known as a helping verb, is a verb that helps to conjugate the compound tenses/moods. The auxiliary verb is conjugated into a particular tense/mood and followed by the past participle of the main verb.

French has two auxiliary verbs: avoir and être.*

For example

• Passé composé
     Il a mangé. - He ate.
     Il est parti. - He left.
• Pluperfect
     Il avait mangé. - He had eaten.
     Il était parti. - He had left.
• Past conditional
     Il aurait mangé. - He would have eaten.
     Il serait parti. - He would have left.

*Most verbs require avoir as auxiliary; only a few dozen have être as the auxiliary. And a few verbs have different meanings depending on the auxiliary verb.