Taste buds are the clusters of sensory cells, housed in small bumps called papillae on the tongue and elsewhere in the mouth, that detect the chemical signals we perceive as taste. Each bud contains receptor cells tuned to the basic tastes — sweet, salty, sour, bitter, and umami — and relays signals to the brain via nerves. Humans have several thousand taste buds, and their density and sensitivity vary between individuals, which is partly why people differ in how they experience bitterness or sweetness. Taste buds regenerate every week or two, so taste recovers after burns or illness. They work together with smell — which supplies most of what we call flavour — to guide eating.