We're walking sweat machines, with two to four million sweat glands on our bodies. We are designed to perspire all day and night, whether you're aware of it or not.
Sweating can be a an unpleasant physical response, we'd overheat without it. Our natural body temperature is 37 degrees Celsius and whenever we rise above that level - because of physical or emotional stress, sweat allows us to cool back down.
Hot weather and intese exercise are the most obvious ways of dialing up your body temperature, but there are many basic bodily functions that have the same effect. Even your stomach breaking down your lunch produces sweat - here are the four key sweat spots to keep an eye on.