CD-i Ready is a compact disc format for mixing audio and data content on a CD.
CD-i Ready places the software and data in the pregap of track 1 (index 0).
[1] Since most CD players assume that the pregap area contains only silence, they skip it.
Because of this, CD-i Ready was presented as an alternative to CD-i (which stores data in the regular indexes of the first tracks of a disc), which was more compatible with audio CD players.
Apart from CD-i Ready and CD-i, these formats include mixed mode CDs and the Enhanced Music CD format.