What are the four primary roles of sweating? 

The four primary roles are:

1. It regulates the body's temperature.
2. Release of excess salts and toxins. (This is also the reason why sweat smells terrible.)
3. The body's smell transmits signals. (Mainly to the opposite sex.) 
4. In response to stress or fear, sweating helps keep people alert. 

There is often sweating in high fever situations, which serves two primary purposes: natural cooling of the body and removing salts and toxins. Drinking a lot is designed to allow sweating without losing significant amounts of fluid in the body.