Vin doux naturel (VDN) is a style of lightly fortified wine, typically made from white Muscat grapes or red Grenache grapes in the south of France.
Other wines, like those of Rivesaltes AOC, can be made from red or white grapes.
[1] The Grenache vins doux naturels can be made in an oxidised or unoxidised style whereas the Muscat wines are protected from oxidation to retain their freshness.
[2] Specific substyles, depending on AOC, include five colors: blanc (white), rosé (pink), ambré (amber), grenat (garnet), tuilé (tiled); and two further qualifications: hors d'âge (beyond age), and rancio [fr] (rancid, "mellowed with age").
The production of vins doux naturels was perfected by Arnaud de Villeneuve at the University of Montpellier in the 13th century and they are now quite common in the Languedoc-Roussillon region of southern France.