You have around 4000 taste buds, spread over your tongue, mouth and throat. Each taste bud contains up to 100 taste receptor cells, which respond to different substances in your food. These taste cells send information about the type and amount of substance to your brain. Tastes are traditionally divided into four categories: salty, sweet, bitter or sour. However, some tastes, like tea and ginger, don't seem to fit, and the Japanese consider the flavour of monosodium glutamate to be distinct from other salty tastes.