When do I use the imperfect tense?

There are three main uses for the imperfect tense:For descriptions in the past e.g. C'était une expérience incroyable (it was an incredible experience)For repeated actions in the past e.g. Je jouais au tennis pendant trois ans (I played tennis for three years)For interrupted actions in the past e.g. Je mangeais mon dîner quand le Le téléphone a sonné (I was eating my dinner when the phone rang