Medicare supplements, also known as Medigap plans, are additional insurance policies designed to fill the gaps in coverage left by Original Medicare (Parts A and B). Offered by private insurers, these plans help pay for out-of-pocket costs such as deductibles, copayments, and coinsurance.

Key points about Medicare supplements:

1. Complement Original Medicare: Medigap plans work alongside Original Medicare to cover expenses that Medicare doesn't fully pay for. A+B covers 80%. Medigap plans cover the remaining 20%.

2. Standardized plans: Medigap plans are standardized by the federal government, meaning each plan provides the same basic benefits regardless of the insurance company offering it.

3. No network restrictions: Generally, you can see any healthcare provider who accepts Medicare, as Medigap plans don't have network restrictions.