If you follow the business side of the music, you may have run across the term “SoundScan.” This is the system by which physical music sales (CDs, vinyl, cassettes, DVDs) are counted.
Before SoundScan was introduced in America on March 1, 1991, album sales were based on rough estimates. Numbers could be misinterpreted or, at worst, manipulated, often in a very corrupt way.
SoundScan eliminates that because a sale only counted when the bar code of the CD is swiped across the scanner at the cash register. That data is sent to a central office where it’s tabulated with all the other data coming in from other stores. The result is a very accurate count of all the albums sold.
Now you know what they mean when someone says an artist has “scanned 400,000 copies.”