When do you use the pretérito perfeito and when the imperfeito?
The pretérito perfeito reports a completed event; the imperfeito describes the surrounding situation. Say what happened with the perfeito, and what things were like, what used to happen, or what was going on when something interrupted with the imperfeito.
Events against background
The perfeito carries the narrative and the imperfeito sets the scene. Portuguese alternates between them constantly, and a passage written in only one reads as broken even when each sentence is defensible.
Chovia quando saí.
It was raining when I left.
Eu lia quando o telefone tocou.
I was reading when the phone rang.
Fui ao mercado e comprei pão.
I went to the market and bought bread.
Habits and descriptions
Repeated past actions take the imperfeito, matching English used to. So do descriptions of age, weather, appearance and feeling.
Quando era criança, jogava futebol.
As a child I used to play football.
Fazia frio e eu estava com medo.
It was cold and I was afraid.
The compound past is not the same as Spanish
Portuguese tenho falado does not mean I have spoken in the Spanish or English sense. It means I have been speaking repeatedly and recently. A single completed past action takes the simple perfeito, which is a real difference from Spanish usage.
Falei com ele ontem.
I spoke to him yesterday.
Simple perfeito for a single event.
Tenho falado com ele.
I have been speaking to him (repeatedly, lately).
Not a one-off.
Common mistakes
Ontem eu lia por duas horas.
Ontem eu li por duas horas.
A stated, finished duration is a completed event.
Quando era criança, fui à praia todo verão.
Quando era criança, ia à praia todo verão.
Todo verão marks a habit, which takes the imperfeito.
Tenho falado com ele ontem.
Falei com ele ontem.
The Portuguese compound past means a repeated recent action, so it cannot take a one-off time marker like ontem.
Frequently asked questions
Why is tenho falado different from Spanish he hablado?
Portuguese narrowed the compound past to repeated or continuing recent action, while Spanish kept it for single completed events. This is one of the traps for Spanish speakers, because the forms look identical and the meanings are not.
Is there a quick test?
Ask whether you are saying what happened or what things were like. A boundary — a start, an end, a stated duration — signals the perfeito.
Do Brazil and Portugal differ here?
Not substantially for these two tenses. The compound past behaves the same way in both.