1. It’s used to describe completed actions or events which occurred once or several times in the past. While if they happened regularly the imperfect tense is used. Compare:
Visité a mi madre dos veces el año pasado. (I visited my mother two times last year).
Visitaba a mi madre todas las semanas cuando vivía en Madrid. (I visited my mother every week when I was living in Madrid.)
2. The action may continue for a while, although the length of time is defined:
Pasé tres meses en Madrid. (I spent three months in Madrid).
La película duró dos horas. (The film lasted two hours).
3. For questions and negatives, you don’t need “did” and “didn’t”:
¿Bailaste con Carla? (Did you dance with Carla?).
No bailé con Carla. (I didn’t dance with Carla).
4. It is normally used with temporal expressions, such as:
Ayer (yesterday) | Anoche (last night) | El lunes (on Monday) |
Hace dos años (two years ago) | El mes pasado (last month) | En 1969 (in 1969) |