What is the difference between the Perfect (Passé Composé) and Imperfect (Imparfait) tenses?

The perfect and imperfect tenses are both used to describe the past, but in different situations. The perfect tense is used to describe a completed action in the past, for example, what you did this morning (Avant d’aller à l’école, j’ai pris le petit déjeuner), what you did at the weekend, or what you did last summer. In contrast, the imperfect is used to describe background actions in the past (Il faisait soleil) , actions which happened regularly in the past, actions with an undefined end point, or something that happened on an ongoing basis.