How is perspiration related to recovery after exercise?

Sweat or perspiration occurs when the body’s core/internal temperature rises. This phenomenon naturally occurs to help maintain and control the regular body temperature of humans. Without sweat, the body will over heat and may lead to heat exhaustion, heat stroke, or worst, death. Sweat glands that cover the entire body are responsible for perspiration to maintain its homeostasis; as the water in the sweat evaporates, the surface of the skin cools, regulating and maintaining overall body temperature.

Perspiration/sweat is mostly composed of water but it also contains some salts that are dissolved and evaporated as well on the skin.