when do you use the imperfect tense
When is the imperfect tense used?
5 Answers
Oversimplified version: the imperfect is used to describe situations in the past and the preterite is used to describe events in the past. Which one to use has more to do with what you are saying than what happened, since many things can be viewed as either situations or events.
Here is an overview from SpanishDict's Reference Library. =)
Hope it helps!
You use the imperfect tense to describe an ongoing past action with no reference to its beginning or end.
Example: Sandra esperaba al doctor -Sandra was waiting for the doctor.
2.)You use it to express habitual past actions and events.
Example: Cuando era joven, jugaba al tenis When I was young, I used to play tennis.
3.)Describe physical and emotional states or characteristics
La chica quería descansar. Se sentía mal y tenía dolor de cabeza. The girl wanted to rest. She felt ill and has a headache.
The imperfect tense is used to describe habitual or repeated actions in the past. For example, if you used to go to the store every day when you were little, you could say, "De niño, yo iba al mercado todos los días." It is also used to describe emotional or physical states or conditions in the past. For example, to say, "I loved my grandmother," you would say, "Yo le amaba a mi abuela." To say, "She was blond," you would say, "Ella era rubia." The imperfect is used to describe weather, and so if it was raining yesterday, you would say, "Llovía ayer." It is almost always (if not always) used with the past progressive.
The preterite, the other indicative past tense, is used to describe something that happened once and (usually) something that happened el año pasado, ayer, anoche, or at some other specific time in the past.
And so, if you say "Yo chocaba el coche," you are saying that you used to crash your car (all of the time!). "Yo choqué el coche," on the other hand, indicates that you crashed the car once.
I believe that there may be other rules (it's been a little while since I've studied this), but those are the basic guidelines. I hope that this helps!
This is quite a big topic. The point of it being, when do you use the preterite and when do you use the imperfect? The imperfect is conveying a sense of inability to pinpoint when you did something. For instance: "I played basketball as a kid," or "Jugaba el baloncesto cuando yo era un niño." There was no general time that says that I played it on, say, July 7, 1998. The same is true with age, since you are that age for an entire year: "I was fifteen years old last year." or "Tenía quince años el año pasado."
Another way to use it is to think it as the English phrase "used to" or "was doing" You would use it when you used to do something, or when you were doing something: "I used to have a lot more friends." "Tenía más amigos que ahora." "I was cleaning the house when my wife arrived." "Limpiaba la casa cuando mi esposa llegó." Notice how llegó was in the preterite rather than the imperfect. If it was, it would be kind of like saying: "I was cleaning the house when my wife was arriving." It just doesn't make as much sense.
There are other general rules to the imperfect, but I don't know them all by heart. I hope I was able to help. 
