The American Psychiatric Association (APA) is the main professional organization of psychiatrists and trainee psychiatrists in the United States, and the largest psychiatric organization in the world. It has more than 38,000 members who are involved in psychiatric practice, research, and academia representing a diverse population of patients in more than 100 countries. The association publishes various journals and pamphlets, as well as the Diagnostic and Statistical Manual of Mental Disorders (DSM). The DSM codifies psychiatric conditions and is used mostly in the United States as a guide for diagnosing mental disorders.