Possessive pronouns replace a noun already known to avoid repeating it. They indicate that something belongs to someone, like a book, a car, or an idea, but they do not name that thing a second time. In 'It’s my book' followed by 'It’s mine', the pronoun takes the place of the noun already understood. Without it, the sentence becomes heavier and repeats the same noun unnecessarily. Possessive pronouns therefore serve to reprise the possessed thing while keeping the link with the possessor.

The possessive pronoun agrees with the noun it replaces, not with the possessor. If the replaced noun is masculine singular, one chooses a form like 'mine' or 'yours'. If the replaced noun is feminine singular, one chooses 'mine' or 'yours'. For a plural noun, a plural form is used, like 'mine' or 'theirs'. The possessor remains the same, but the form changes according to the object or person possessed. It is the same principle as for Possessive adjectives, where the agreement is also with the possessed noun.

In the singular, the forms change according to the gender of the replaced noun. For a masculine singular noun, one uses 'the mine', 'the yours', and 'the his'. For a feminine singular noun, one uses 'the mine', 'the yours', and 'the hers'. We say 'This pen is mine' but 'This jacket is mine'. The difference between 'mine' and 'mienne' clearly shows the gender of the noun being referred to. The forms with 'le' replace a masculine noun, those with 'la' replace a feminine noun.

In the plural, the possessive pronoun takes a form that corresponds to the number of the replaced noun. For a masculine plural noun, one uses 'the mine', 'the yours', and 'the theirs'. For a feminine plural noun, one uses 'the mine', 'the yours', and 'the theirs'. We say 'These books are mine' and 'These photos are mine'. The plural does not depend on the number of possessors, but on the noun being referred to. A single possessor can have multiple objects, and the pronoun will then be in the plural.

Possessive pronouns are usually preceded by the definite article 'the'. We say 'the mine', 'the yours', 'the ours', 'the theirs'. The article is part of the form used with the pronoun. It allows the announced implied noun to be understood and gives the sentence a complete form: 'I take mine', 'They chose theirs'. This construction is often found in everyday language when the possessed noun is already evident in the situation. It is useful with repetitions of Personal pronouns or of nouns already mentioned.

To choose the right form, first look at the replaced noun, then its gender and number. For a masculine singular object, we say 'the mine', 'the yours', 'the his'. For a feminine singular object, we say 'the mine', 'the yours', 'the hers'. For several masculine objects, we say 'the mine', 'the yours', 'the theirs'. For several feminine objects, we say 'the mine', 'the yours', 'the theirs'. In 'Your hat is black, mine is white', 'hat' is masculine singular, so the form is 'the mine'. In 'Your keys are here, mine are in the car', 'keys' is feminine plural, so the form is 'theirs'.

'Mon', 'ton' and 'son' are possessive adjectives. They always accompany a noun: 'my brother', 'your bag', 'his idea'. The possessive pronoun, however, replaces the noun: 'mine', 'yours', 'his'. One cannot say 'my' by itself, but one can say 'the mine'. Compare: 'This book is mine' and 'This is mine'. In the first sentence, the noun 'book' is present. In the second, the noun is omitted because the pronoun takes its place. The same opposition exists with Demonstrative pronouns and Indefinite pronouns, which also replace a noun instead of accompanying it.