The fluid or moisture secreted from the sweat glands to the surface of the skin (through skin pores) during perspiration
Sweat is the byproduct of perspiration. It is released by the body of certain animals primarily to regulate body temperature especially as cued by external factors such as humidity and ambient temperature. Another factor that incites the body to secrete sweat is physical or emotional stress.
Sweat is comprised mainly of water. It also contains small amounts of solutes (about 0.2-1%).1 When one sweats, the body is losing both water and solutes but water is the main component that is primarily lost relative to the amount of solutes lost. Also, the amount of solute that is lost varies. In a cold environment and the absence of exercise, not much sodium is lost (~<5 mmols/day).1