Red bone marrow is a type of tissue found in certain bones, primarily responsible for producing blood cells. It contains hematopoietic stem cells, which develop into red blood cells, white blood cells, and platelets. This process is crucial for maintaining a healthy blood supply and supporting the immune system. In adults, red bone marrow is mainly located in the pelvis, sternum, ribs, and the ends of long bones like the femur. As people age, some red bone marrow is replaced by yellow bone marrow, which is primarily composed of fat cells and does not produce blood cells.