A gland is a small organ in your body that makes and releases specific substances your body needs. Think of glands as tiny factories, each one producing something different: sweat glands make sweat to cool you down, salivary glands in your mouth produce saliva to help you chew and digest food, and tear glands (also called lacrimal glands) make tears to keep your eyes moist and wash away dust.

Your body contains many different glands. Some release their products directly into your bloodstream. Your thyroid gland, for instance, releases hormones that help control how your body grows and uses energy. Others release substances through small tubes or openings, like the oil glands in your skin that keep it from drying out.

You probably notice your glands working every day without realizing it. When you get nervous before giving a presentation, your sweat glands activate. When you smell fresh cookies baking, your salivary glands start producing saliva. When you're fighting off a cold, glands in your neck might swell as your immune system battles the infection. Each gland has its own specific job, and together they help keep your body running smoothly.