In your culture, do you use the same words when speaking to people of the same of age as you do when speaking to someone older?
In French, there are two ways of addressing people, depending on the relationship between the two people. With friends or family, you use the "tu" form (Quel âge as-tu ? Comment t’appelles-tu ? D’où viens-tu ?). The "tu" form is used to address people the same age or younger, whether you know them or not. The "tu" form is also used to speak to older family members, or to older colleagues and close friends who’ve asked to be said "tu" to.
To address people who are older, have a higher rank in the company, or people in public places (in stores for example) for the first time, the polite plural form "tu" (Quel âge avez-vous ? Comment vous appelez-vous ?).
In the beginning of a working relationship, people say "vous" to each other, even if they are the same age.
Be careful! These rules for polite address are not this strict in all French-speaking countries. In Quebec and Africa, the "tu" form is used much more readily. In African culture, using the "tu" is proof that the person spoken to is no longer considered a stranger but a friend. However, in Belgium and in France, the use of the "vous" form is standard.