Learn Italian: Mio fratello è partito per Parigi.

In Italian, the past tense (passato prossimo) is usually formed with the helper verb avere (to have). However, for verbs that describe movement from one place to another, like partire (to leave), we must use essere (to be) instead. So, literally, the structure is "My brother is left".

What if my sister left for Paris? Would the verb change?

Yes! When you use essere as the helper verb, the past participle (the main action verb, like partito) has to match the subject's gender and number. If it were your sister, the ending would change to match a feminine singular subject: Mia sorella è partita. Because fratello is masculine singular, it ends in -o (partito).

Why isn't there an article before Mio fratello? Shouldn't it be Il mio fratello?

Normally, Italian possessives do need an article, like in il mio gatto (my cat). But there is a major exception: singular close family members (like fratello, sorella, madre) do not take an article. So it's just mio fratello.

Why is it per Parigi instead of a Parigi? Don't we use a for cities?