Earlier this afternoon, in a different thread, (the "what is on your mind?" thread), a poster asked what the difference was between German and Belgian beer:
I answered as follows, and think that this post also belongs here, where others, more knowledgeable than I, may well add to it:
I'm not an expert, just an enthusiastic (and fascinated) amateur, with an interest in history and an absolute fascination with the history of food and drink.
German brewing and beer are governed by the beer purity law, known as the Reinheitsgebot, which dates from 1516.
Obviously, this beer purity law pre-dated German unification, but came to cover the entire country (and still does) post unification (in 1871, and, more recently, in 1990).
This law aimed to protect consumers (drinkers) on grounds of price, and quality: Prices were set, wheat was prohibited (to reserve it for baking bread), and - with the exception of three ingredients - all other ingredients from the flavoursome - caraway, apples, fruit, - to the downright dodgy - were prohibited (and still are).
For years, only three ingredients, barley, hops, and water were allowed when brewing beer; latterly, wheat (which had been prohibited in the original Reinheitsgebot in order to reserve wheat for baking bread), has been permitted - originally, in Bavaria (where they have long - long predating Bavaria becoming part of Germany - brewed their famous wheat beers - Weissbier etc), and now, nation wide.
However, to this day, German beer can only be brewed from these four ingredients: Malted grains (barley or wheat), hops, water and yeast (the role of yeast in brewing hadn't been fully understood in 1516).
German beer styles include clear beers (Helles, and Pils, among others) and well known lager styles - plus, the more cloudy styles that include Weissbiers (which are usually wheat beers).
They also brew dark beers. Weihenstephaner brews a dark (dunkel is the word used to describe it) beer, as does Erdinger; actually, Weihenstephaner brews a number of dark beers - a "Traditional Bayerische Dunkel" and a dark Weissbier, their "Hefeweissbier Dunkel".
They brew bock, and dopplebock (double bock) style beers, which are both dark and strong, (and often, seasonal specialities).
Their bock and dopplebock styles are not unlike the Belgian "dubbel".
Most German towns and cities and areas will have (will brew) their own local versions of beer styles that are popular nation wide, and there will be some specific regional specialities as well.
In the 1980s, the German brewing industry sought to protect access to the German beer market by prohibiting the sale of other beers (stating that they didn't meet the purity law requirements); citing open markets, free trade, and rights to market access, the EU challenged this national monopoly. The German argument was that this was not a national protection racket (although almost everyone suspected that this is exactly what it was), but an insistence on consumer and brewing industry protection by maintaining brewing standards, and that any foreign beer that met these purity (natural product) requirements could also enjoy (untrammeled) access to the German beer market and could be openly sold in pubs and off licences.
In any case, in practice, this meant most beers were denied access to the German beer market (which was, and is, vast, and thus exceedingly profitable), but this also meant that Guinness (which also uses only natural ingredients) could enjoy access to the German market (if you are going to use purity standards - rather than nationality, which was illegal under market access & free trade rules in the EU - as your reason for excluding foreign beers from your market, you must admit those foreign beers which do meet this requirement), which is why Irish pubs also appeared in Germany as long ago as the 1980s.
Now, because Belgium does not have a beer purity law, Belgian breweries have been a lot less confined, a lot less limited, a lot less restricted, in how they could approach the brewing of beer, and what they could add to the beer, and thus, the styles, (and varieties) of beer available in Belgium are far wider (and a lot more alcoholic at the strong end) than what you will find for sale in Germany.
Belgium has thousands of different beers, and they do differ - at times dramatically - from one another, and here, you will find, for example, fruit beer styles, sour beers, dark beers, lager style beers, session beers, as well as the legendary 'dubbel' beers (which are dark, and range from 6.5-7.7% abv) 'tripel' beers, (which are light in colour but high in alcohol, and would range from 8.0-9.5% abv), and the superlative 'quadrupel' beers, which are both very dark and very strong (clocking in at around 10-11.5% abv).
I've been in Belgian pubs where the beer list is as large, and as heavy, and as endless, as a telephone directory (for those who remember what that was).
To my mind, many of the best of the Belgian beers come from Trappist monasteries or abbeys - monks brewing beer to fund the needs and upkeep of the monasteries - and their standards are superb.
To be defined as a Trappist beer, a beer must be brewed in the vicinity of the monastery (or abbey), or actually in the monastery, the brewing process must be (either) supervised by - or carried out by - the monks, and the profits should be intended for funding the needs of the monastic community, and for charitable works and development projects compatible with the Trappist order's own specific rules.
Some of the best known (and highly regarded) Belgian beers are Trappist beers: For example, Rochefort Trappistes, Westmalle, Orval, Chimay etc.
St Bernardus (which is not Trappist, but which brews beer to that standard) has had close links with Westvleteren - which is Trappist, and which nowadays produces tiny amounts of (difficult to find) beer - (and which is also regarded by some as possibly the best beer in the world). Westvleteren releases (small) amounts of (much sought after) beer to the market when they are in need of funds. Otherwise, one must travel (in person) to the monastery - and its adjacent shop/store - to acquire some of their legendary beer.
At one stage, St Bernardus actually brewed their (Westvleteren) beers under licence, (a time, I suspect, when Westvleteren needed market exposure and sales in order to obtain funds for monastery refurbishment). Even now, the St Bernardus Abt 12 is supposed to resemble (or is said to derive from) the legendary Westvleteren Trappist 12.
