Whilst both the preterite and the imperfect express actions that have happened in the past, their uses vary significantly.The preterite is used to describe actions that have happened one time, a closed and completed action. For example: Yesterday I went shopping=ayer, fui de compras or last week I went to the cinema=la semana pasada fui al cine.However, the imperfect is used for habitual actions, that kept happening in the past (repeated actions). For example: When I was younger, I used to play games=Cuando era más joven, jugaba juegos. The imperfect is also used to describe, for example: There were many people on the bus= Había mucha gente en el bus.