Digital music made a giant leap 11 years ago this week, when annual sales figures for 1988 revealed that compact discs for the first time had outsold vinyl records.

While major record companies touted the superior sound quality of CDs, their embrace of the digital format inadvertently laid the groundwork for today's grass-roots MP3 phenomenon.

In 1987, sales of LPs and CDs were neck and neck, with vinyl slightly in front, according to the Recording Industry Association of America. Just one year later, CD sales doubled that of their vinyl counterparts, 150 million copies to 72 million.

That surge was led in part by music fans replacing scratchy vinyl records with CD versions of the same albums. There were also big CD sales numbers for such hits of the time as Aerosmith's Permanent Vacation (1987), which included the singles "Dude (Looks Like a Lady)" (RealAudio excerpt), "Angel" and "Rag Doll."

Cassettes remained the dominant format for a few years, but by 1993, CDs were outselling them, too, and vinyl records had become a rare sight in music stores.

Meanwhile, the seeds of today's online music revolution were being sowed. Because CDs store music as digital information, their songs can be easily converted to the MP3 format and transferred quickly across the Internet, with little loss of quality (and often without regard to copyright laws).

A quick search of popular MP3 pirate sites will turn up downloadable copies not only of current hits but also of songs such as Guns N' Roses "Sweet Child o' Mine" (RealAudio excerpt) and George Michael's "Faith" — both from albums that helped drive CD sales past vinyl 11 years ago.

In other digital music history, Dec. 31, 1988, saw the first DAT (digital audiotape) master, made at a Grateful Dead New Year's Eve concert. While thousands of listeners at home taped — on hissy cassettes — an FM broadcast of the Oakland, Calif., show, "DAThead" tapers exchanged precise digital clones of the soundboard mix.