The reason we sweat is to control our body heat. When the body gets overheated, the skin produces sweat. It evaporates using up the heat of the body, thus bringing the body heat down.
Sweating is caused by millions of minute glands that are scattered throughout the skin. There are two types of sweat glands, the eccrine and the apocrine. The ecrine glands are found throughout the human skin, and they produce the greatest amount of sweat. Both the temperature at the body surface and emotions stimulate them into action. The apocrine glands are found in places like the armpits and nipples. They are made active by strong emotions like anger, fear etc..
Sweat, by itself, does not have any odour. But once it reaches the skin surface, it can have an offensive smell, from the action of bacteria.
