Answer: Vinyl Records

In the early 1990s consumers were buying Compact Discs hand-over-fist–the cassette was dying as a music format and purchasing new albums on vinyl was a niche hobby. The total global vinyl record sales in 1993, for example, barely broke a quarter million units.

What was the listening venue of the aging and the painfully hip, however, started to catch on with the masses. Over the ensuing two decades, vinyl record sales went from barely scraping a quarter million units to, by the end of 2012, breaking 4.6 million sales worldwide.

Also noteworthy about 2012 is that total album sales (Compact Discs, digital album purchases, etc.) were down across the board, while vinyl LPs increased 15% between 2011 and 2012. It might be the way your grandfather listened to his favorite albums, but vinyl is back in a big way.