When to use the perfect tense versus the simple past (Perfecto vs Indefinido)

European Spanish (Español peninsular) uses two different tenses to talk about past events in cases where in English we generally use one. Knowing whether to use El Pretérito Perfecto ("he ido") or El Pretérito Indefinido ("fui") can be tricky at first but it's actually pretty easy.

The rules are simple once you understand how we think about units of time: days, weeks, months and years.

Detailed explanation

In English, we would use I went for all of these cases:

In Español peninsular, however, we choose either He ido or Fui according to when the action occurred relative to the "unit of time" referred to or implied (day, week, month, year):

How to know when to use El Pretérito Perfecto or El Pretérito Indefinido

The choice of tense depends on whether the speaker is "still inside" the "unit of time" that's being used or implied:

If we're expressing ourselves in blocks of days then "yesterday" is in the past relative to today and therefore requires "fui". If we're talking about exactly the same event but using the time block "this week," then that is still current because the event and the speaker are in the same time block, so the speaker uses "He ido". Easy!

English is not so different

You might think this concept of time blocks determining choice of tense is strange at first, but in fact, in English we use the perfect tense with the very same time blocks (albeit with a different nuance; i.e., to introduce a new fact or express a sense of continued action).

These sentences sound right:

But these sound strange:

They feel very strange because the time block is over. Spanish is the same: don't use El Pretérito Perfecto to talk about events in previous blocks of time. Use El Pretérito Indefinido instead.