It is a feeling of fear, dread, or apprehension about something that might happen in the future. Anxiety disorders are the most common form of emotional disorder and can range from generalized anxiety disorder (GAD), which is excessive worrying about everyday life, to more specific phobias, panic disorders, or social anxiety disorders. Symptoms of anxiety can include nervousness, restlessness, a sense of impending doom, increased heart rate, rapid breathing, sweating, trembling, and difficulty concentrating.