I found this at Allmusic.com:
"...He found his saving grace in hip-hop, starting out as a DJ and human beatbox, and later moved into rapping for a greater share of the spotlight, taking his name from the DMX digital drum machine (though it's also been reinterpreted to mean "Dark Man X"). He made a name for himself on the freestyle battle scene, and was written up in The Source magazine's Unsigned Hype column in 1991. Columbia subsidiary Ruffhouse signed him to a deal the following year, and released his debut single, "Born Loser." However, a surplus of talent on the Ruffhouse roster left DMX underpromoted, and the label agreed to release him from his contract. He issued one further single in 1994, "Make a Move," but was convicted of drug possession that same year, the biggest offense of several on his record.DMX began to rebuild his career with an appearance on one of DJ Clue?'s underground mixtapes. In 1997, he earned a second major-label shot with Def Jam, and made a galvanizing guest appearance on LL Cool J's "4, 3, 2, 1." Further guest spots on Mase's "24 Hours to Live" and fellow Yonkers MCs the LOX's "Money, Power & Respect" created an even stronger buzz, and in early 1998, he released his debut Def Jam single, "Get at Me Dog." The song was a gold-selling smash on the rap and dance charts, and paved the way for DMX's full-length debut, It's Dark and Hell Is Hot, to debut at number one on the pop charts."