The usage of tu and vous depends on the kind of relationship (formal or informal) that exists between the speaker and the person with whom they are speaking and the age differences between these subjects.
Ce is primarily used as a "neuter" pronoun to refer to events and situations: « J'ai vu Jean hier.
Neologisms such as iel(le), ille, ul, ol and yul have emerged in recent years as gender-neutral alternatives to the masculine and feminine pronouns, but are not yet considered standard in French [2] despite their use in some speech communities.
To erase sexism,[clarification needed] a neutral plural pronoun such as iels can be used by some French people.
The subject pronoun on (from Old French [h]om, homme 'man', from Latin homo 'human being') takes third-person singular verb forms in the same way that il and elle do, and is used: It is never used for the number one, or as in one of them.
Le, la, and les are not used when the direct object refers to the same entity as the subject; see § Reflexive pronouns, below.
When an indirect object pronoun is used, it replaces the entire prepositional phrase; for example, « Je lui ai donné un livre » ("I gave him a book").
Lui, leur, and y are replaced with se (s' before a vowel) when the indirect object refers to the same entity as the subject; see § Reflexive pronouns, below.
For example, « Un voyageur sait se sentir chez soi n'importe où », "A traveller knows how to feel at home anywhere."