The human tongue is capable of distinguishing just four basic tastes. Its surface is covered by thousands of nerve endings called taste buds, which are divided into four different groups.

Thos on the tip of the tongue sense sweetness and those at the back sense bitterness.  The ones at the sides sense saltiness and sourness. There are other taste buds scattered around the inside of the mouth. The main tasters of sour and bitter are actually in the roof of the mouth.

So things like honey and sugar are tasted with the tip of the tongue. However beer, which can have a bitter taste, is best enjoyed with the back of the tongue. Specialist beer tasters will tell you to drink it by pouring it to the back of your tongue, avoiding the tip.  Salty crisps and chips are tasted by the side of the mouth and things like sour lemons, vinegar and things like that also get tasted by the taste buds at the sides.

More complex tastes are made up of combinations of the basic four flavours.  Young adults have around 8000 taste buds, but the nerve endings start to die after the age of 45, so that older people usually have only around 6500 taste buds.

Much of what we perceive as flavour in food is in fact a mixture of taste and smell, which is why food seems to lose its taste when the nose is blocked during a cold.

Damage to taste buds can be very painful and make it very difficult to taste food properly. Even those very tiny ulcers that sometimes affect the tongue can badly affect the ability to taste.