Hildegard Peplau developed the theory of interpersonal relations, which views nursing as an interpersonal process focused on the nurse-client relationship. The theory outlines phases of the relationship - orientation, identification, exploitation, and resolution - and roles for nurses, such as stranger, teacher, and counselor. Peplau believed the relationship and roles help clients address problems, gain independence, and terminate the relationship successfully. The document provides an overview of Peplau's theory and concepts, and explains their application in nursing assessment, diagnosis, and care planning using an example client case.