The relative pronoun links two clauses and avoids repeating a noun already known. It replaces this noun in the second clause and keeps the link with it. In la maison que j’ai visitée, que replays la maison and connects the two ideas into a single sentence. Without this pronoun, you would have to repeat the noun or make two separate sentences. The relative pronoun thus introduces a subordinate clause that specifies the preceding noun. It is often used with information of time, place, possession or function, and it also prepares more complex structures with Propositions et Subordonnées.

Qui replaces the subject of the verb in the relative clause. The resumed noun performs the action, and qui takes its place. In l’homme qui parle, it is the man who speaks. In les enfants qui jouent, it is the children who play. After qui, the verb agrees normally with its subject, because qui represents that subject. It is used with people, animals or things. The pronoun remains always invariable. This form is easily recognized when you can reformulate the relative with the noun as subject. It functions like the other reprise pronouns, in the manner of the Pronoms.

Que replaces the direct object of the verb in the relative clause. The resumed noun does not perform the action, it receives it. In le film que nous regardons, le film is being watched. In la lettre que j’écris, la lettre is written. After que, the subject of the verb often follows immediately, which helps to recognize the function. The pronoun elides before a vowel and becomes qu’: l’idée qu’il propose. Que remains invariable. It is often useful when you want to specify a noun with an action detail, as with the Pronoms démonstratifs, which also reprise a noun already presented.

Dont replaces a group introduced by de, de la, du or des in the relative. It avoids repeating the preposition and the noun. In le livre dont je parle, we talk about this book. In la femme dont j’ai vu la voiture, the relationship with de is already carried by dont. It is used with verbs, nouns and adjectives built with de. It is also used to express possession: l’enfant dont le père travaille ici. Dont remains invariable. It concentrates a sense of connection, origin or theme without redoing the construction with de.

Où reprises a place or a moment in a relative clause. It means then in which, to which, at the moment when or the day when depending on the context. In la ville où je suis né, où reprises a place. In l’année où nous sommes arrivés, it reprises a time. The word remains invariable. It is not limited to a concrete location: it can also introduce a period, a date, a situation or a precise moment. It is chosen when the reference point serves as the frame for the action of the relative.

After a preposition, one often uses lequel and its forms to avoid ambiguity. We say le pont sur lequel nous marchons, la personne avec laquelle je travaille, les maisons devant lesquelles il s’arrête. The preposition stays in front of the relative pronoun. This form appears when qui or que are not enough to clearly show the link. With things or ideas, lequel is common after sur, dans, avec, sans, pour, par, sous or devant. It helps keep a sentence clear when several nouns could be understood.

Lequel agrees in gender and number with the antecedent it replaces. The masculine singular gives lequel, the feminine singular laquelle, the masculine plural lesquels, the feminine plural lesquelles. The form is chosen according to the noun replaced, not according to the preposition. We say la table sur laquelle le vase repose and les chaises sur lesquelles nous nous asseyons. When the preposition ends with à or de, the form often contracts: auquel, à laquelle, auxquels, auxquelles; duquel, de laquelle, desquels, desquelles. The agreement always follows the antecedent noun.

Quoi appears mainly after a preposition when no other relative pronoun fits. It is found in fixed expressions like ce à quoi je pense, voilà de quoi il s’agit, les raisons pour quoi in archaic or very limited uses. In everyday language, quoi mainly reprises a thing, an idea or a fact after à, de, pour, sans. It does not inflect and remains invariable. It is often used when the antecedent is vague or expressed by a neutral demonstrative, as in ce dont je parle and ce à quoi je pense, where the sentence structure imposes the choice of the relative pronoun.