Anxiety is a sort of a natural reaction to danger, sudden mental attacks, body’s automatic fight-or-flight response i.e. triggered when you feel being threatened internally, under pressure, or feeling like facing a challenging condition, such as job interview, examination, or first date or anything you're afraid to perform in front of people (stage show, etc.). In the moderation, it (Anxiety-attack) is not necessarily considered a bad thing. It can help to stay alert and focused, spur you to action, and motivated you to solve the problems you are being afraid of. But when anxiety is constant or overwhelming—when worries & fears interfere with your relationships, Daily-activities and daily life this means you've now dived into the territory of an anxiety disorder from the normal stage of anxiety disorder.