The "passé composé" is a French verb tense used to express actions that have been completed in the past. It is formed using an auxiliary verb, either avoir or être, followed by the past participle of the main verb. For example, in the sentence "J'ai mangé" (I ate), "ai" is the auxiliary verb, and "mangé" is the past participle of manger. This tense is commonly used in spoken French and is essential for storytelling. It indicates specific events or actions that occurred at a definite time, such as "Elle est allée au marché" (She went to the market). Understanding the "passé composé" is crucial for effective communication in French.