Sweating just means your body is effectively cooling itself.

Why do we sweat?

Because it is useful for the body. Sweating is a completely physiological phenomenon, the body is reacting to the outer and inner factors. It is a natural way of balancing body temperature. Intensity of sweating depends on physical strains, psychological tension, diet, consumption of some drugs, age and outside condition, like relative humidity of air, temperature, room ventilation, polluted atmosphere.