Modern beer styles are a fundamental language for beer geeks and professionals alike. Brewers use these guidelines to give their products a clear identity, competition organizers use them to categorize entries, judges rely on them to evaluate quality, and consumers use them to navigate their purchasing decisions.

The relationship between beer and its defined styles is often compared to the chicken and egg debate, though the reality is much simpler.

Today, the two most prominent sets of standards are the Beer Judge Certification Program (BJCP) and the Brewers Association (BA) guidelines, both of which utilize a mix of quantitative and qualitative measurements. Quantitative measurements are objective values that can be measured with scientific equipment, such as alcohol strength, colour range, and measurable bitterness. These values are used by brewers during production and by judges to verify if a beer fits technical parameters.

Qualitative measurements rely on human sensory perception and are more difficult to measure mechanically, encompassing appearance, aroma, flavor, and mouthfeel. While consumers use these traits to decide if they enjoy a beer, judges use them to determine if a beer is true to its style.

The BA and BJCP guidelines emerged in the late 1970s and 1990s, respectively, but serve different purposes. The Brewers Association guidelines were founded on the work of legendary journalist Michael Jackson, who was instrumental in categorizing world beer styles. These are tailored for commercial brewers and are often the first to add trendy or emerging styles. On the other hand, the BJCP guidelines grew out of the American Homebrewers Association and are designed for homebrew competitions and judge education. They tend to be more academic and descriptive.

Before modern, structured styles existed, beer classification was a pragmatic matter driven by taxation, regional origins, and technology.

Geography acted as the primary arbiter of style, meaning a beer was simply defined by the resources, water profile and malt available in the town where it was brewed. Names like Burton, Dortmund, or Pilsen were regional designations long before they were universal categories.

Several styles have vanished because of shifting geopolitical conditions; for instance, Brohan was lost when the city of Einbeck’s brewing infrastructure was destroyed during the Thirty Years’ War, and Kotbusser disappeared when the German Purity Law was strictly enforced across a unified Germany.

Historically, beers were also classified by strength. In the 18th and 19th-century UK, the X system was used to denote quality, where a single X was a basic small beer and multiple Xs indicated a strong ale. This was often tied to the shilling system, which categorized beers by their tax bracket.

A similar concept exists today with Trappist beers like Westvleteren and Rochefort. The numbers 6, 8, and 10 originally represented strength through Belgian Degrees, which was a simplified way of expressing the Original Gravity. While alcohol levels have shifted over the decades due to improved brewing efficiency, the numbers remain a legacy of that gravity-based naming convention.

Beyond strength, drinkers distinguished beer by age, where Mild historically referred to young beer and Stale or Stock beer had been matured in wood. Even the distinction between ale and beer was once a matter of law, with the former originally being unhopped.

Some beer styles treated as distinct today were once identical. In England, stout began as a strong porter, and while they are now distinguished by roast character, they were used interchangeably in the 19th century. Similarly, pale ale and bitter overlapped significantly, with Bitter becoming the standard name for draught beer and Pale Ale reserved for bottled versions.

The evolution of names like Fuller’s London Pride reflects a linguistic shift from technical terms to marketing. While the ancestor of these beers was Pale Ale, customers used the nickname Bitter to describe the hop character. As the word bitter began to face a marketing problem with international drinkers, the industry started adopting the term Amber Ale to make the style more approachable.

For Belgian Blonde, Belgian Tripel, and Belgian Golden Strong Ale, modern guidelines treat them as separate, yet they were all originally brewed with the goal of creating golden beers to compete with the popularity of pale pilsners. While they are considered different styles now, many Belgian consumers consider Belgian Tripel and Belgian Golden Strong Ale to be in the same tradition.

Today, one can find dozens of IPA variations like Hazy, West Coast, or Cold IPA in guidelines, yet some breweries simply label them as Hoppy Ale commercially. Most consumers may recognize these beers as fruity and bitter without even bothering to distinguish the sub-styles.

While development of styles helps differentiate taste and define competition parameters, the question of whether similar styles have become too separated and confusing for the consumer remains a valid philosophical discussion.