The term "bitter" has been used in England to describe pale ale since the early 19th century.
Although brewers used the term "pale ale", before the introduction of pump clips, customers in public houses would ask for "bitter" to differentiate it from mild ale; During the 20th century, bitter became the most popular type of draught beer sold in British pubs and has been described as "the national drink of England".
In Scotland, bitter is known as either "light" or "heavy" depending on the strength, colour and body. Bitter is traditionally cask conditioned and either dispensed by gravity through a tap in the cask or by a beer engine, although in recent decades, bitter has also been pasteurised and carbonated, or sold in bottles or cans, which affects the flavour.
Despite the myth, bitter should not be served warm, but at "cellar temperature" of 11° to 14° Celsius (50° to 55° Fahrenheit). ] Bitter belongs to the pale ale style and can have a great variety of strength, flavour and appearance from dark amber to a golden summer ale. It can go under 3% abv and as high as 7% with premium or strong bitters.
The colour may be controlled by the addition of caramel colouring. Sub-types of bitter British brewers have several loose names for variations in beer strength, such as ordinary, best, special, extra special, and premium. The difference between an ordinary and a best bitter is that one particular brewery's best bitter will usually be stronger than its ordinary, and premium bitter stronger again.
Hop levels will vary within each sub group, though there is a tendency for the hops in the session bitter group to be more noticeable.
Drinkers group the beers into five categories:
A low alcohol bitter, often bottled.
Session or ordinary bitter
Strength up to 4.1% abv.
A number of British beers with the name India Pale Ale will be found in this group, even though they little resemble the traditional style of IPA or its modern incarnation.
IPAs with gravities below 1.040° have been brewed in Britain since at least the 1920s.
This is the most common strength of bitter sold in British pubs.
Best or special bitter
Strength between 4.2% and 4.7% abv.
In the United Kingdom bitter above 4.2% abv accounted for just 2.9% of pub sales in 2003.
The disappearance of weaker bitters from some brewers' rosters means "best" bitter is actually the weakest in the range. Premium or strong bitter Strength of 4.8% abv and over.
Extra special bitters or golden ales
Also known as Extra Special Bitter, or in Canada and the US, ESB. Golden ale Golden or summer ale has an appearance and profile similar to that of a pale lager.