The compact disc turned 30 on Oct. 1. Back on Oct. 1, 1982, Sony began selling the world's first commercially available CD player.
Let's not forget the overall importance of the CD. Unlike its predecessor, the cassette, the CD was designed to be a higher-quality audio format than LPs (audiophiles to this day debate that point, vehemently). But what most people liked about the CD was its convenience—here was a small, reasonably durable piece of plastic that allowed you to skip from track to track, and no need to flip vinyl.
Besides new-music sales, the CD contributed to the coffers of record companies and retailers by making most consumers go out and repurchase their music collection. Getting people to pay twice for the same album, along with new music throughout the '90s, boosted revenue for record companies and retailers alike. Hundreds of billions of CDs have been sold over the format's lifetime.
The CD was also the first popular recording format that was entirely digital, replacing analog audio waves with ones and zeros. Digital encoding was heralded by the music industry as the higher-fidelity future, but the industry forgot one thing: While those ones and zeros were most efficiently stored on plastic discs for the first 20 years of the CD era, such things as the Internet and tinier, cheaper hard drives would make it easier to send that data directly to a person's computer than to the local Tower Records.
Initially, the CD was the music industry's savior, but encoded in those ones and zeros was also its demise.