Professor Aaron T. Beck is the first person who has worked on the method of cognitive behavioral therapy (CBT) to use on patients suffering from depression. He developed CBT in the early 1960s when he was a psychiatrist at the University of Pennsylvania. He researched, developed and tested the efficiency of the method used on patients. This method focuses on how thinking affects the way a person feels and acts, and helps to change their thinking, behavior, and emotional responses to become more rational. Later studies show that CBT is the best method for major depression. CBT has been widely used by psychiatrists and psychotherapists for the treatment of depression. This therapy has helped more than 120 million people suffering from major depression and reduced the rate of suicide among more than 1 million people worldwide every year. Professor Beck has become known as the Father of Cognitive Behavioral Therapy.