An underground CD, usually in the styles os Hip Hop, R&B, Reggaeton, or Dirty South. A mixtape is made by a DJ, and consists of songs that are remixed, or old beats to new songs. Sometimes they feature regular tracks of an unkown artist, so he/she can get press.
"Hey yo, I got this new mixtape by DJ J-Fizzy Wanna! It's hot, and it has a remixed Fat Joe song!"