Original Medicare Part A & Part B is a health insurance program for people age 65 or older. However, there are exceptions, you can qualify if you've been on Social Security disability for at least two years. Also those with permanent kidney failure.

The initial Medicare enrollment period - turning age 65 is during the 7-month period that begins 3 months before the month you turn 65. Includes the month of your birthday turning 65. The 3 months after the month you turn 65.
The Annual Enrollment Period- every year from October 15- December 7th. You can make changes in your Medicare Advantage (Part C) and your Prescription Drug Plan (Part D). 

If you're 65 and not getting Social Security benefits you may not be automatically  enrolled in coverage so you will need to sign up for Medicare Part A (Hospital insurance) and Part B (Medical  insurance).
If you qualify Part A is no charge. The Medicare charge for Part B in 2021 is $148.50 per month.

You can call Social Security to ask questions or sign up for Medicare over the phone.
1-800-772-1213
Or you may also apply and start an online application for Medicare enrollment for Part A and/or Part B. Click below to go to the Social Security website for the online application. SocialSecuritywebsite.

Medicare Part A – is coverage for hospital insurance. The Hospital deductible for each benefit period is $1,484 in 2021 for Original Medicare. It covers inpatient hospital, hospice care, nursing facility are and some types of home healthcare.
Medicare Part B – is coverage medical insurance . This covers doctors’ services, medical supplies, outpatient care and preventive services. The annual Original Medicare deductible is $203 for 2021.

Medicare Part C - Medicare Advantage plans offered by private companies that have contracted with Medicare to provide individuals with all of their Medicare Part A and Part B benefits often times including dental and vision. Types of organizations that cover Medicare Advantage plans include (PPO) preferred provider organizations, (PFFS)private fee-for-service plans and (HMO)health maintenance organizations.
Medicare Part D – is a Prescription drug plan. Private insurance companies offering stand alone prescriptions plans with copays and deductibles. Some Medicare Advantage Plans have prescription drugs Part D coverage(MAPD). Medicare Supplement Plans do not have Part D included. You must get a separate stand alone Prescription drugs plan.