In French, the verb savoir (meaning “to know” or “to know how to”) is an irregular verb in the passé composé. It uses the helping verb avoir and its past participle changes from savoir to su. The conjugation follows the pattern: j’ai su, tu as su, il/elle a su, nous avons su, vous avez su, ils/elles ont su. The verb is used to describe something that someone knew or found out in the past.