Hemoglobin is a protein rich in iron and is the pigment that gives blood its distinctive red hue. Hemoglobin is responsible for providing blood its characteristic color. It is in charge of carrying oxygen throughout the body, beginning in the lungs and working its way toward the extremities. Anemia can develop for a number of fundamental reasons, the most common of which are excessive blood loss, insufficient formation of red blood cells, and a high rate of breakdown of red blood cells.