What is the difference between the passé composé and the imperfect tenses in French?

Both of these tenses are used to refer to actions in the past. The first one, the passé composé, is used to refer to completed actions, things that happened at a specific point in time. The imparfait, or imperfect tense, is used for repeated actions, habits and descriptions in the past.Here is an example which demonstrates the difference:la téléphone a sonné quand j’étais dans la cuisineThe telephone ringing is a single completed action which happens at a specific point of time so it takes the passé composé. The second verb is in the imperfect as it the background description which is interrupted.