According to the features present on mammography, the breast is classified into 4 types. - Type A: consists almost entirely of fatty tissue - Type B: scattered areas of fibroglandular tissues - Type C: almost entirely consists of fibroglandular tissue - Type D: very dense breast Reference: https://www.mayoclinic.org/tests-procedures/mammogram/in-depth/dense-breast-tissue/art-20123968#dialogId7175509 Image via: https://www.mayoclinic.org/tests-procedures/mammogram/in-depth/dense-breast-tissue/art-20123968#dialogId7175509