Spanish has many more tenses than English, and that may confuse English speakers. A few years ago I posted a series of Spanish tense-conjugation lessons that include 22 different tenses. And I still omitted at least a couple. Of course, some tenses are not so much used. However, Pretérito Indefinido and Pretérito Imperfecto are two of the most important ones.
Pretérito Indefinido Vs. Pretérito Imperfecto (WTF!!!)
In English, both tenses correspond to the Simple Past. But in Spanish there is a contextual difference between them.
For example:
Yo fui a la escuela = I went to school – Here I’m not implying whether I went to school last year, yesterday, this morning, or 20 years ago. I’m also not suggesting whether I still go to school or not.
Yo iba a la escuela = I went to school (also: I used to go to school) – Here I’m suggesting that the action happened in a past that seems like it has changed. So I’m implying that this happened long ago, and/or this doesn’t happen anymore. Thus, probably I don’t go to school anymore. Also, Pretérito Imperfecto suggests a repetition or regularity, while Pretérito Indefinido suggests a one time event.
Yo fui a la escuela = I went to school – I’m just referring to 1 time I went to school.
Yo iba a la escuela = I went to school – I’m referring to a habit or recurrence. I’m talking of a time I used to go to school.
Don’t miss to ask if you have questions
The videos above proved a comprehensive explanation and examples regarding this topic. Based on my student’s feedback it seems like this time I hit the bullseye trying to clarify this matter. But don’t hesitate to write or comment if you have any questions.