Sweat glands are small structures in the skin that produce sweat, helping to regulate body temperature. There are two main types: eccrine glands, which are found all over the body and release a watery fluid, and apocrine glands, located mainly in areas like the armpits and groin, which produce a thicker secretion. When the body heats up, the nervous system signals these glands to release sweat. As the sweat evaporates from the skin's surface, it cools the body down. This process is essential for maintaining a stable internal temperature, especially during exercise or hot weather.