What is the difference between the passé composé and the imperfect tense?

The two most important past tenses in French are the passé composé (perfect) and the imperfect.

When you’re talking about something that happened in the past, you use the passé composé to describe a completed event e.g. I went to the football match/Je suis allé au match de foot. This event happened once and is now finished - its consequences do not continue into the present. You form the passé composé with a subject pronoun (je/tu/il/elle), an auxiliary verb (être/avoir) and a past participle (e.g. allé)

The imperfect is often used in descriptions and refers to an event which happened regularly or continuously in the past. It can also mean something that ‘used to’ happen. It is formed with a subject pronoun (je/tu/il/elle) and a conjugated form of the infinitive e.g. donner – il donnait.

The imperfect is also used with the passé composé to indicate things that were happening when something else took place e.g. He fell in love when he was watching a film with Marie/Il est tombé amoureux quand il regardait un film avec Marie.