Passé composé vs imparfait

French often uses two past tenses together. The choice is not just about time; it is about how the speaker presents the action.

The core contrast

Use	Tense	Example
A completed event	passé composé	J'ai ouvert la fenêtre. — I opened the window.
Background, description, habit, ongoing state	imparfait	Il faisait froid. — It was cold.
An event that interrupts background	passé composé	Je lisais quand Paul est arrivé. — I was reading when Paul arrived.

Common patterns

• Use imparfait for age, weather, feelings, descriptions, and repeated habits: Quand j'étais petit, je jouais dehors.
• Use passé composé for a sequence of completed actions: Je suis entré, j'ai posé mon sac, puis j'ai appelé Marie.
• Some verbs can use either tense depending on meaning: Je voulais partir (I wanted to leave) vs J'ai voulu partir (I decided/tried to leave).

Watch out

Do not translate English past forms mechanically. "I was tired" is usually J'étais fatigué, but "I got tired" would be Je me suis fatigué or another completed-event form depending on context.