Sweat, we do it when it’s hot, or when we exercise. It’s part of the body’s method for regulating our temperature. Moisture, and some salts, are released from millions of glands in our skin, the evaporation of this moisture cools the body. If we don’t sweat, we don’t cool, if we don’t cool we overheat and that is not a good thing.
So, what’s the problem? The problem is that in our modern ultra-sterile world sweat is seen as something unpleasant, and best avoided. To this end there are countless products designed to stop us sweating, they’re called antiperspirants; "anti" meaning against, and "perspirant" meaning sweat, or what comes out when we perspire. These products stop us sweating, but sweating is essential for our body to regulate it’s temperature, it is bad for our health if we don’t sweat.