Dr. Elisabeth Kübler-Ross's book, "On Death and Dying," focused on introducing the stages of grief. These stages, also known as the Kübler-Ross model, are a series of emotional stages experienced by individuals facing impending death or other significant losses. The five stages are denial, anger, bargaining, depression, and acceptance. This model has been widely used to understand and cope with the emotional responses to loss and terminal illness. It is essential in the fields of psychology, counseling, and healthcare to recognize and support individuals going through the grieving process. The book is a significant contribution to the understanding of death and the emotional journey associated with it.