When do I use the imperfect tense?

The imperfect tense is used when there is no definite conclusion to an action or event- the event/action took place over an undefined period of time, without a distinct knowledge of it ending:e.g/ 'I used to play squash' - Je jouais au squash-You USED to play squash, and do not play it either as much currently, or at all; notice here how there is no definite conclusion of stopping squash entirely: therefore the imperfect tense best fits here.Note also that 'Je jouais au squash' can also be translated as 'I was playing squash...(when)'- if an action is interrupted and is not fully completed, the imperfect tense is best to use.e.g/ 'I was playing squash when I saw my friend'- Je jouais au squash quand j'ai vu mon ami. (The imperfect tense also works well when describing previous feelings and with particular phrases)