The All Music Guide provides a short history of this dance music form. Select "Rock" from the top menu on this site, then click on "90s" from the list of decades. Then, choose "Trance" from the list of 90s styles. Log on and read up on the German origins of this type of music. This is a helpful site for those researching the history of rock and roll.
While this is a commercial site that sells trance music CDs and offers reviews, it also offers links to many resources like picture galleries, downloadable collections of trance mp3s, and other trance Web sites that also offer information and news. The site contents are helpfully classified into trance, acid jazz, ambient, techno, and others.