A diaphragm is a muscular structure that separates the thoracic cavity from the abdominal cavity in mammals. It plays a crucial role in respiration by contracting and relaxing to facilitate inhalation and exhalation. Additionally, the term "diaphragm" can refer to various other contexts, such as the diaphragm in Photography, which controls the amount of light that enters a camera. In some medical contexts, it may also refer to a contraceptive device used to prevent pregnancy.