Bitter is one of many styles of ale or beer. Bitter beer is close in style to pale ale. Some of the other more common styles of beer in the UK are mild, stout, porter and strong ale.

The main ingredient (other than water) is malted barley, with hops added only to improve the keeping properties and give a distinctive smell and taste.

Bitter covers a wide variety of taste, aroma and appearance. These include copper, malty, dry and sweet, while some have the aroma of hops. In Northern England the bitter tends to have a creamy collar (sometimes called a head) induced by pulling the beer through a tight sprinkler, whilst in South East England the beer is generally more hoppy and served with a natural head.