Passé composé

When

Usually an event in the past that you see as finished. Hier, j'ai vu un film. (Yesterday I saw a film.) Also for something in the past with a result now: J'ai perdu mes clés. (I have lost my keys.)

How to form it

Avoir or être in the présent + past participle (parlé, fini, vendu).

Pitfalls

• English always uses "have", but French chooses between avoir and être. I have gone, but je suis allé. A useful rule of thumb: être goes with a fixed list of verbs that mostly express a movement or change (aller, venir, partir, arriver, entrer, sortir, monter, descendre, tomber, naître, mourir, rester, devenir, retourner, rentrer, passer, and compounds such as revenir) and with all reflexive verbs (je me suis levé). Not every verb of movement belongs: j'ai marché, j'ai couru.
• Watch out: monter, descendre, sortir, rentrer, retourner and passer take avoir when a direct object follows: je suis sorti, but j'ai sorti la poubelle (I took the bin out).
• With être the participle agrees with the subject: elle est allée, ils sont partis.
• French uses the passé composé where English uses the simple past: Hier, j'ai mangé une pizza is "Yesterday I ate a pizza".