Past tense

When discussing something that happened in the past, like "I went to the store yesterday," the typical verb forms you might use are the simple perfect preterite, the imperfect preterite, and the composed perfect preterite. Formally, the distinction is in whether it is a single action that began and ended in the past (perfect: I went to the store), a repeated, continuous, or habitual past action (imperfect: I've been going to the store), or an action that began in the past and either just ended or is ongoing (composed perfect: I've gone to the store). In practice, usage varies a bit.

FRENCH: The simple perfect is called the passé simple, and the composed perfect the passé composé. In spoken language, the passé composé is nearly always used in place of the passé simple, and has been since about the 12th century. You might use the passé simple orally when you're telling a story, but not, I think, when it's a casual story about what you did last weekend. In writing (novels and, I believe, formal/academic writing), you'd use the passé simple 'properly', and not replace it with the passé composé.

The imperfect is called the imparfait and behaves normally.

ITALIAN: The simple perfect is called the passato remoto, and the composed perfect the passato prossimo. As in French, one replaces the other in colloquial usage, but which replaces which varies geographically. To the north of Italy, passato prossimo is used for both cases; to the south, passato remoto is used for both cases.

The imperfect is called the imperfetto and behaves normally. However, there's another imperfect formed with the imperfect of essere and the gerund. So when you say "I was talking to him all yesterday," you might say "io parlavo," or you might say "io stavo parlando."

SPANISH: The simple perfect is called the pretérito perfecto simple, and the composed perfect the pretérito perfecto compuesto. In Spain and to a lesser extent in Mexico, they're used 'properly', but in most other forms of Spanish, the pretérito perfecto simple is used for both cases.

The imperfect is called the pretérito imperfecto and behaves normally.

PORTUGUESE: The simple perfect is called the pretérito perfeito, and the composed perfect the pretérito perfeito composto, but the composed perfect doesn't have the same meaning as in the other Romance languages. The pretérito perfeito is used both for actions that began and ended in the past and for actions that began in the past and ended just now or are ongoing (so covering both cases, like the passé composé in oral French).

The pretértio perfeito composto shows an iterative aspect – so "tenho ido à loja" means "I've been going to the store," but it does not mean "I went to the store." You couldn't use the pretértio perfeito composto to talk about a discrete action that began in the past and ended just now. It's for recurring stuff.

The imperfect is called the pretérito imperfeito and behaves normally. However, just as in Italian, there's another imperfect formed with the imperfect of estar and the gerund. So when you say "I was talking to him all yesterday," you might say "eu falava," or you might say "eu estava falando."

In Brazilian Portuguese, this is much more common than the 'proper' imperfect in informal usage, both oral and written. Specifically, you'd say "eu falava" of something that happened multiple times in the past ("we talked a lot in college"). This is similar to the pretérito perfeito composto ("we've been talking a lot"), but for things that have ended. You'd use "eu estava falando" for an action that was ongoing while something else happened ("I was talking to him while I made dinner"), or that happened once, but in an ongoing way ("I was talking to him yesterday" as opposed to "I talked to him yesterday" – one is an ongoing state, one is a one-and-done thing that happened).