Original Medicare consists of Parts A and B. These are sponsored by the government.
It is important to understand that Original Medicare (Parts A and B) does not cover all of your medical expenses. Because of this, other Medicare plans exist to help provide additional coverage for those who need it.
Part C, or Medicare Advantage, plans are private health plans. This Medicare insurance plan includes coverage for everything Part A and Part B cover, and sometimes Part D, depending on the plan.
Part D, or Prescription Drug Coverage, plans are also private health plans. They offer coverage for prescription drug costs.
Medicare Supplement (Medigap) plans help pay some costs not covered by Original Medicare Parts A and B. Medigap plans are private health plans as well.