American Association of Retired Persons.
It's a powerful political lobby, created to look out for the interests of people who have left the work force, and who may therefore need governmental help in sustaining them when they are no longer suited to provide for themselves.
In practice, it tilts the political playing field to the financial advantage of older members of society, such as I am.
Ah, thanks for the explanation, which pretty much explains why I never heard about it. So they try to garner members by their mailings?
Judging by other replies their works is not universally acclaimed...
(3) AARP also airs a lot of time on the TV, so mailing and internet are not the only ways they advertise.A couple of things:
(1) AARP sends out many physical mailings -- asking for donations, offering insurance plans, etc. -- so the volume of waste paper that the recipients need to throw away (or "recycle") is large. Many national organizations do the same: I have heard that the NRA ("National Rifle Association") does this as well; and of course any alumni get voluminous mailings from the universities from which they graduated. The volume of the mail is not a distinguishing characteristic of the AARP, because so many other groups follow the same practice; but it is a characteristic. If it irks a lot of people, that's because they mail to a lot of people.
(2) AARP lobbies (attempts to persuade) Congress for financial advantage for older people. Some of the results may be beneficial to the nation, but some of them may be obstacles to fairness.

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