Anxiety can be a normal reaction to stress. It can help us deal with a tense situation, study harder for an exam, or keep focused on an important speech. In general, it can help us cope. But when anxiety becomes excessive, irrational dread of everyday situations, it has become a disabling condition. Examples of anxiety disorders are obsessive-compulsive disorder, post-traumatic stress disorder, social phobia, specific phobia, and generalized anxiety disorder. Symptoms of these disorders begin in childhood or adolescence.
For the full Fact Sheet from The national Institute of Mental Health, click on the link above.