Anxiety is the feeling of worry, nervousness, or unease, typically about an imminent event or something with an uncertain outcome. With an anxiety-related disorder, your fear or worry does not go away and can get worse over time. It can influence your life to the extent that it can interfere with daily activities like school, work and/or relationships.

Anxiety disorders are the most common mental illness in the U.S., afflicting over 40 million American adults.

Source: Anxiety Org