Exhalation is the act of breathing out, releasing air from your lungs after you've inhaled. Every time you breathe, you go through two steps: inhalation (breathing in) and exhalation (breathing out). When you exhale, your chest relaxes and pushes air up through your throat and out through your nose or mouth.

You can feel exhalation working when you blow out birthday candles, sigh after a long day, or fog up a window with your breath. Athletes learn to control their exhalation: a swimmer exhales underwater to release used air before surfacing to inhale fresh air again. Singers and musicians who play wind instruments practice long, controlled exhalations to hold notes steady.

While we usually don't think about exhalation since it happens automatically, it's just as important as inhalation. Your body uses inhalation to take in oxygen, and exhalation to get rid of carbon dioxide, the waste gas your cells produce. Without both parts working together smoothly, you couldn't survive for more than a few minutes.