in addition to the top of their tongue, humans also have a few taste buds on the lips (especially salt-sensitive ones), the inside of the cheeks, the underside of the tongue, the roof of the mouth, and the back of the throat.
the sensation of taste, like all sensation, resides in the brain. But the interesting thing about a taste bud is that its location in the mouth determines how something will taste. Different areas ofthe tongue respond to different tastes-bitter, sour, salty, sweet. See the diagram below.