Anxiety is a warning sign that warns of impending danger and prepares a person to deal with it. Lack of anxiety makes people face considerable problems. Therefore, anxiety, as a part of every human's life, forms one of the components of his personality structure and thus provides the possibility of a longer, more productive and fruitful life. Although a certain amount of anxiety can be constructive and useful, but this state may find a chronic and continuous aspect, in which case anxiety becomes morbid and a wide range of anxiety disorders ranging from cognitive and physical disorders to fears. They are unjustified and cause widespread panic. In this research, anxiety disorders in the DSM-5 classification have been investigated. Epidemiology of psychiatric disorders is a branch of research in behavioral sciences that examines the way these disorders are distributed in society. Although the existence of mental illnesses in different societies has been confirmed centuries ago, it was during the 20th century that statistical methods were used to estimate the volume of these problems.