Indefinido and imperfecto
The past tenses (Pretérito indefinido/pretérito Imperfecto)
In Spanish, when we tell a story, we alternate between two different past tenses. The past tenses are called pretéritos.They are the pretérito indefinido (compré, trabajé, fui, hice) and the pretérito imperfecto (compraba, trabajaba, íbamos).
This is one of the difficulties for most Spanish students, since the difference between these two tenses exists in only a few languages.
The answer to this problem is much easier than what we get from most explanations in any grammar book we find.
To understand this difference we need to comprehend what an action in the past is (indefinido) and what descriptions, situations and habits in the past are (imperfecto).
You can get more details on this by watching our YouTube video.
Click on this link to check the video: El pasado en español