Pre-Revolutionary France had possibly one of the less codified systems of titles and names of European countries. Except for within the Royal Family, and for the very highest titles, the application of family titles and names was not systematic. Most people associate the particle de with nobility, and although most aristocrats did use the particle, there were many, many commoners whose names contained the particle as well. The particle served to indicate origin, and in the case of nobles, referred to the fief or fiefs possessed by the family. A family descended from a baron de Montreuil, for example, would all be named N. de Montreuil. When a family acquired other titles, the name tended to become more complicated. Let's say a Louis de Montreuil acquired the title of comte de Balbec, his son might be known as Jean de Montreuil, Jean de Montreuil de Balbec, Jean de Montreuil-Balbec, or Jean de Balbec, depending on the situation. There was not very much consistency. I have seen Marie de Rabutin, daughter of the baron de Chantal, and marquise de Sévigné, referred to in correspondence as Mlle de Chantal, Mlle de Rabutin, Marie de Rabutin de Chantal, Mme de Sévigné, etc. Sometimes, over time, a family would use its second title as its name exclusively, while retaining a sense of belonging to an original house. As far as titles are concerned, all noble titles were attached to a piece of land, and ownership of the land automatically allowed use of the title, assuming the owner of the land was noble to begin with (the exception being duc, or duke). At one time ownership of a fief automatically implied nobility, but as commoners were coming up in the world, buying more and more land, it was decided that buying a noble fief didn't automatically confer nobility. Mme d'Etioles became Mme de Pompadour by acquiring the estate of Pompadour, for example. In the case of duc, however, acquiring a duchy did not automatically confer ducal status; one had to be created a duke by the king. This was because dukes tended to be peers, which allowed them a seat in the Parlement of Paris, and because dukes automatically outranked all other nobles; most nobles ranked according to the status of their family, not according to a fixed table of precedence based on title. Much of this information applies only to pre-Revolutionary France, as Napoleon and Louis XVIII changed a lot of the rules, or applied them more regularly. | 
