What is the difference between the perfect and the imperfect tense and when is it appropriate to use them?

In French, there are two primary tenses which are used to express something that happened in the past. These are the perfect and imperfect tense, referred to in French as le passé composé and l'imparfait. The perfect tense generally refers to actions that have just happened in the immediate past, usually once and at a specific time. For example:Je suis allé au supermarché- I went to the supermarket. The imperfect tense generally refers to habitual actions in the past or narrative description. For example:J’allais au supermarché- I was going to the supermarket. To make it clearer, let’s combine these two tenses together to highlight their differences:Hier, j’allais au supermarché quand j’ai vu mon ami Pierre. Yesterday, I was going to the supermarket when I saw my friend Pierre.The difference between the two tenses should be fairly clear here. The imperfect tense is used to describe something that was happening (I was going) whereas the perfect tense is used to describe something that has happened (I saw) . It is not always easy to decide when to use which tense, but these simple rules apply to the vast majority of cases in French.