How can I distinguish between the preterite and the imperfect in Spanish?

Hello, Rachel! Despite the fact that there are lots of specific rules on when to use each one of them, we could sum it up by saying that: - The "pretérito perfecto simple" is used to talk about actions in the past which are finished. For example: ayer fui al supermercado. - The "pretérito imperfecto" is used to describe actions which are part of a rutine in the past (cuando era pequeño, iba al parque todos los días), to tell a story (el gato jugaba con el perro), or, finally, to describe characters or objects of the story (la mujer tenía el pelo negro). I hope I have helped you! :) Xiana