The relative pronouns connect a subordinate clause to a known antecedent. They avoid repetition and specify which being, which object, which place or which idea is involved. The relative pronoun follows immediately its antecedent and introduces the relative.

Who replaces the subject of the relative clause, for a person, a thing or an idea. That/which replaces the direct object of the relative clause, and it is often followed by a past participle that may agree when the object is placed before the verb, as in Pronoms compléments. After it's, we prefer what and which to present a general idea.

IdéeIdea	ExempleExample
Qui remplace le sujet de la relative.Who replaces the subject of the relative clause.	La fille qui rit est contente.The girl who laughs is happy.
Que remplace le complément d'objet direct de la relative.That/which replaces the direct object of the relative.	Le film que j'ai vu était court.The film that I saw was short.
Après c'est, on préfère ce qui ou ce que.After it's, we prefer what and what to present a general idea.	Ce qui m'étonne est son calme.What surprises me is his calm.

Dont replaces a complement introduced by de, which expresses possession, the link or the verb parler de. Where replaces a complement of place or time. In a familiar register, que can sometimes replace dont in speech, but the standard form remains dont.

IdéeIdea	ExempleExample
Dont remplace de avec un complément.Dont replaces de with a complement.	L'auteur dont je parle est célèbre.The author whom I am speaking about is famous.
Dont peut marquer la possession.Dont can mark possession.	La maison dont le toit est rouge est ancienne.The house whose roof is red is old.
Où remplace un lieu ou un moment.Where replaces a place or a time.	Le jour où nous sommes partis était pluvieux.The day when we left was rainy.

After a preposition, such as à, de, pour or sur, one uses lequel, laquelle, lesquels or lesquelles. These forms agree with the noun in gender and number. When the preposition contracts, you get forms like auquel, duquel or auprès duquel.

IdéeIdea	ExempleExample
Lequel s'accorde avec le nom repris.The lequel agrees with the noun it refers to.	La chaise sur laquelle je m'assois est neuve.The chair on which I sit is new.
Auquel suit la préposition à.To which the preposition à follows.	Le projet auquel je pense avance vite.The project to which I am thinking advances quickly.
Duquel suit la préposition de.From which the preposition de follows.	Le livre duquel je parle est rare.The book I am talking about is rare.

What, which, and of which are used to refer to a general idea, a fact or a situation when there is no precise antecedent. What acts as the subject, what as the direct object and of which as a complement introduced by de. These forms are useful for expressing abstract thought or a sentence starting with 'it's'.

IdéeIdea	ExempleExample
Ce qui reprend une idée sujet.What acts as the subject.	Ce qui me plaît est la clarté.What I like is clarity.
Ce que reprend une idée objet direct.What acts as the direct object.	Ce que j'attends, c'est une réponse.What I expect is an answer.
Ce dont reprend une idée avec de.Of which acts as a complement introduced by de.	Ce dont je rêve est la paix.What I dream of is peace.

Meaning and agreement in relative clauses: Restrictive relative clauses identify the antecedent precisely and do not use a comma, whereas explanatory relative clauses add secondary information and are enclosed in commas. The position of the relative immediately after its antecedent helps to understand the meaning and the connection. With que, the past participle agrees if the direct object is placed before the verb, which is essential for reading and writing correctly.

IdéeIdea	ExempleExample
La relative restrictive précise l'antécédent sans virgule.The restrictive relative clause identifies the antecedent without a comma.	Les livres que tu as choisis sont utiles.The books you chose are useful.
La relative explicative ajoute une information avec virgule.The explanatory relative clause adds information with a comma.	Mon frère, qui habite Lyon, arrive demain.My brother, who lives in Lyon, arrives tomorrow.
Le participe passé s'accorde avec que placé avant le verbe.The past participle agrees with que when placed before the verb.	La lettre que j'ai écrite est partie.The letter I wrote has gone.

Qui, que, dont, où and the forms after prepositions cover most of the relative clauses of everyday French. The choice depends on the role of the word referred to in the subordinate clause, then on the possible presence of a preposition. The neutral form ce qui, ce que, ce dont remains the most natural after it's and for general ideas.