Learn Italian: Ci siamo ritrovati dopo il liceo. - We met again after high school.

Ritrovarsi is being used as a reciprocal verb here, meaning 'to find each other' or 'to meet again'. In Italian, all reflexive and reciprocal verbs must use essere (in this case, siamo) as their helping verb in the past tense (passato prossimo).

Why does ritrovati end in -i instead of -o?

Because the helping verb is essere, the past participle (ritrovati) must agree with the subject in gender and number. Since ci (we) is a plural subject, the ending changes to the plural -i (assuming a masculine or mixed-gender group).

How does the prefix ri- change the meaning of the verb?

Adding ri- to a verb in Italian often means 'again', similar to 're-' in English. While trovarsi means 'to meet up' or 'to find oneself', ritrovarsi specifically means 'to meet again' or 'to reunite'.

Is liceo the only word for high school in Italian?

Il liceo refers specifically to an academic high school in Italy that prepares students for university. While there are other words for vocational or technical high schools (istituto tecnico, etc.), liceo is the most common translation for the English concept of high school in everyday conversation.