Trance emerged as a form of electronic dance music around 1990, with the advent of music that was essentially techno or house, but had simplified percussion, extreme repetition, and other hypnotic effects such as sustained chords and long echoes. Trance generally has no "thump" in its percussion or "groove" in its basslines -- that is, the hi-hats and the bass in the kick drum are generally de-emphasized as compared to house or techno.
