How are album sales measured? (A few questions.)

[Pupik]

I've always been curious about this, I was hoping someone (any insiders?) could shed light on this question. Is it based on people actually buying the album from the store, or the store buying it from the recording artist's distributor?

Does someone record each and every sale of every album...say, is some still recording whether Pink Floyd's Dark Side of the Moon is moving an album a week in every big city? For that matter, are less notable album sales being notched up and reported? And what happens to recording sales royalties after a musical group "breaks up"?

 

[Gen.]

How much stores buy.

That's why you sometimes see mind boggling amounts of albums being sold even though you know alot of people download the stuff.