Does a person automatically get part A Medicare and then have to apply for part B?

Q) I have a question on a person turning 65. Does a person automatically get part A Medicare and then have to apply for part B? Or do they have to apply for both? What happens if a persont turns 65 and they do not apply- what would happen then?
Thanks.

A) Most people age 65 or older who are citizens or permanent residents of the United States are eligible for free Medicare hospital insurance (Part A). You are eligible at age 65 if:

• You receive or are eligible to receive Social Security benefits; or
• You receive or are eligible to receive railroad retirement benefits; or
• Your spouse receives or is eligible to receive Social Security or railroad retirement benefits; or
You or your spouse (living or deceased, including divorced spouses) worked long enough in a government job where Medicare taxes were paid; or
• You are the dependent parent of a fully insured deceased child.
If you do not meet these requirements, you may be able to get Medicare hospital insurance by paying a monthly
premium. Usually, you can sign up for this hospital insurance only during designated enrollment periods.

PART B

Anyone who is eligible for free Medicare hospital insurance (Part A) can enroll in Medicare medical insurance (Part B) by paying a monthly premium. Some beneficiaries with higher incomes will pay a higher monthly Part B premium. For more information, ask for Medicare Premiums: Rules For Higher-Income Beneficiaries (Publication No. 05-10536) or visit http://www.socialsecurity.gov/mediinfo.htm.