A sweat gland is a tiny organ in your skin that produces sweat, the salty liquid that helps cool your body down when you get hot. You have millions of these microscopic glands scattered across your skin, with especially high concentrations on your palms, the soles of your feet, and your forehead.

Here's how they work: when your body temperature rises (from running around, sitting in the sun, or even feeling nervous), these glands pump sweat through tiny tubes to the surface of your skin. As the sweat evaporates into the air, it carries heat away from your body, cooling you down like a natural air conditioning system.

You might notice that sweat feels different in different places. The sweat glands in your armpits produce a thicker type of sweat that bacteria on your skin can break down, which is what causes body odor. Many of these are a special kind of sweat gland called apocrine glands. The glands on your palms and forehead produce a thinner, clearer sweat, mostly from eccrine glands.

Your sweat glands work hardest when you're exercising or when it's hot outside, but they're always working at least a little bit. Without them, your body would overheat dangerously, the same way a car engine overheats without a cooling system.