Bitter is one of the five basic tastes detected by the tongue, along with sweet, sour, salty, and umami. Bitterness sits at the back of the tongue and is often the slowest-perceived basic taste. In drinks, bitterness comes from various sources: hops in beer (especially IPAs), herbs and roots in liqueurs (Fernet, Campari, amari), tannins in red wine, oak in aged spirits, and certain natural compounds in distillates. Bitter is often a polarising flavour — some drinkers love it (IPA enthusiasts, amaro fans), others avoid it. With 284 mentions across 7 categories on LivCheers, bitter is more concentrated in specific drink types than universal.

While 'bitter' can be a negative descriptor in some contexts (over-extracted wine, off-flavoured beer), it's a positive descriptor in many drink categories. IPA bitterness from hops is the entire point of the style. Amaro and Fernet bitterness comes from carefully selected herbs and is the defining character. Aperitivo culture revolves around the bitter-sweet balance of Campari and similar drinks. Premium dark chocolate is bitter, and so is excellent espresso. The capacity to appreciate bitter character is often a marker of evolving palate sophistication.