The parts of Medicare are parts ABC and D. there are many different alphabetically named Medicare supplement plans. Not all companies offer all plans. And Medicare supplement plan D supplements original government, Medicare A and B and Medicare part D plan is a drug plan for more questions with Medicare if you’re getting ready to start Medicare go to themedicarefamily.com to book a free appointment. We are licensed and all 50 states or call 1-800-970-1964. | The Medicare Family