Generalized anxiety disorder is the most common anxiety disorder, characterized by a constant state of worry lasting over 6 months. Symptoms include restlessness, fatigue, poor concentration, irritability, tension, and sleep disturbances. Panic disorder involves sudden panic attacks that peak within 10 minutes, accompanied by physical symptoms like a rapidly beating heart. Phobic disorders involve irrational fears triggered by specific situations, such as agoraphobia involving fears of situations where escape may be difficult.