tous

In a sentence

• Tous les étudiants sont présents aujourd'hui.

  All the students are present today.

  'Tous' is used to mean 'all' or 'every one' and refers to a group (students in this case). It agrees in number and gender with the noun it modifies, showing inclusiveness.

• Je les ai vus tous hier.

  I saw them all yesterday.

  'Tous' here acts as a pronoun meaning 'everyone' or 'all of them', used for emphasis and positioned after the verb.

• Ils souriaient tous en voyant le film.

  They all smiled when watching the movie.

  'Tous' modifies the subject of the sentence ('Ils'), indicating that every individual in the group performed the action (smiling).