Sometimes the French use nous (we) to designate one person, instead of je (the pronoun I). This practice is known as nous de majesté, nous de modestie or nounoiement. These names (majesty and modesty) have almost opposite meanings because the singular nous can be used in very different ways :

  • when you represent the authority. The kings of France used it, hence the sentence nous de majesté. Officials still use it in decrees: "nous, maire de Paris, décidons de fournir des appartements pas cher à nos enfants..."
  • when you write a book or an article, and you want to say something about you without being too personal. To express a personal belief, you may say: "nous croyons fermement que les résultats macro-économiques de la Politique Agricole Commune, etc". You will use "nous" in an academic thesis, in a newspaper editorial, but certainly not in a Usenet post or an Everything2 writeup.

In short, usage of nous de majesté is very restricted, and most people have never used it in their life. A foreigner should really not bother studying it.

The grammatical problem described in tu versus vous also arises with nous: if there is an adjective, it should remain singular. Therefore the following clause is correct although it may look strange even to French eyes: "Nous sommes persuadé (or persuadée if a woman is speaking) de la validité de notre point de vue".

Remember: if it's simple, it's not French.

Nounoiement was used by the Roman Emperors to give more authority to their decisions. The first Emperor who said nos was Gallienus III.