Anxiety disorder is a type of mental illness which can stop a person from leading a normal life. Anxiety is usually a normal emotion of getting nervous about something that normally people don’t get nervous or scared of. It is often an emotion of serious nervousness and fear which are constant and this can be disabling. For example the fear that sets in before a stage performance or taking an exam. We don’t exactly know the cause of anxiety however it is a type of mental disorder which is result of combination of things like changes in your brain and stress in your environment sometimes in the genes too. Other reasons for this anxiety could be an unknown or known fear. It is also caused by a hyper-active body’s fear-processing system.