The Trappist order originated in the Cistercian monastery of La Trappe in France but Belgian monasteries only started to brew beer in the 19th century.
In 1997, eight Trappist abbeys - six from Belgium (Orval, Chimay, Westvleteren, Rochefort, Westmalle and Achel), one in The Netherlands (Koningshoeven) and one in Germany (Mariawald) - founded the International Trappist Association (ITA) to prevent non-Trappist commercial companies from abusing the Trappist name.
According to the ITA criteria, a Trappist beer is recognized as such only if it is brewed within the walls of a Trappist abbey, by or under control of Trappist monks; the brewery, the choices of brewing, and the commercial orientations must obviously depend on the monastic community and the economic purpose of the brewery must be directed toward assistance and not toward financial profit. There are currently six breweries in Belgium that are allowed to have their products carry the authentic Trappist Product logo:
- Bières de Chimay
- Brasserie d'Orval
- Brasserie de Rochefort
- Brouwerij Westmalle
- Brouwerij Westvleteren
- Brouwerij de Achelse Kluis
Belgium’s Trappist beers are all ales, that is, top fermented, distributed in bottles, and mainly bottle conditioned. Trappist breweries use various systems of nomenclature of the different beers produced, which relate mainly to the relative strength of the beer in the range (e.g., "single", "double", "triple". Colours or numbers can be used to indicate the different types, dating back to the days when bottles were unlabelled and had to be identified by the capsule or bottle-top alone. The number system gives an indication of strength but is not an exact measurement of the alcoholic content.