How do I know the difference between the preterite and imperfect tenses in Spanish?

In most cases, the preterite tense refers to completed actions, which are actions that have definite beginning and end points. Whereas the imperfect refers to actions which are not completed and do not have a definite beginning or an end. They are also used to describing the past and things you 'used to do'.For example, if you wanted to say "Tom ran 5 kilometers" you would use the preterite, because this is a completed action, he hasn't carried on running forever. If you wanted to say "When I was younger, I ran every day" you would use the imperfect, because the sentence is describing an event in the past that someone used to do.To help you, there are lots of useful phrases which indicate which tense is normally used. Here are a few examples:Preterite Triggers Imperfect Triggersla semana pasada cada diaayer todas las semanasanoche a menudo