What is the difference between the perfect and the imperfect tense?

Both the perfect and imperfect tenses are forms of the past tense - for describing events or actions which have already happened. The perfect tense (le passé composé) is used when an action was a one-off event which has been completed. For example: I went to the cinema – je suis allé au cinéma, I ate the sandwich – j’ai mange le sandwich, I did my homework- j’ai fait mes devoirs. As you can see these short phrases are describing things which have already been completed. The imperfect tense (l’imparfait) however describes events which were ongoing in the past (in English these tend to end in -ing) For example: I was going to the cinema - j'allais au cinéma, I was eating the sandwich – je mangeais le sandwich, I was doing my homework – je faisais mes devoirs. As you can see these events were still going on at the time – they were continuous action. It is quite easy to spot the perfect tense as opposed to the imperfect. The perfect tense will always contain either avoir or être conjugated in the present tense (auxiliary verb) followed by the past participle.