REBT was introduced by Albert Ellis and teaches that our thoughts directly influence our feelings and behaviors. It uses the ABCDE technique where A is an activating event, B is one's belief about the event, C are the consequences of that belief, D is disputing irrational beliefs, and E are effective new behaviors. The diagnostic step examines the activating event, irrational belief, and disturbed consequences. Through cognitive and behavioral techniques like cognitive restructuring and systematic desensitization, clients learn to dispute irrational thoughts and overcome fears. REBT has been applied clinically for disorders like depression and anxiety and non-clinically in workplaces.