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

This may seem tough but once you get your head around it, it's really simple!

The imperfect tense is used for actions which occured continously in the past - for example, I used to eat my toast every morning. A clue is to look out for the phrase 'used to' as this will often tell you the imperfect should be used. The imperfect also is used in certain circumstances: 1)Describing the weather eg. Hier, il était beau 2)Giving opinions in the past eg. Le film était fantastique! 3)Descriptions in the past eg. la maison était grande

Remember these rules by thinking of WOD (Weather, Opinions, Descriptions)

The passé composé tense is used when actions happened once in the past and are completed - for example, I ate my cereal this morning.