Anxiety disorders are one of the most common mental illness in the U.S., affecting 40 million adults. But what exactly is anxiety? In this special edition from TIME, anxiety is examined in its complexity. Is it a physiological ailment, or a psychological impairment or both? Is it a simple fight-or-flight response to everyday stress and how best to manage it in our lives? This special edition includes: What anxiety does to your brain and body, the upside of anxiety: how the stress can fuel you, how social media and our digital lives make us anxious, and the unique pressures upon children and teens and how to address them. Also included are natural remedies for anxiety, tips on mindful meditation and more.