Formats that fall under the "enhanced CD" category include mixed mode CD (Yellow Book CD-ROM/Red Book CD-DA), CD-i, CD-i Ready, and CD-Extra/CD-Plus (Blue Book, also called simply Enhanced Music CD or E-CD).
The technology was popular in the late 1990s with the increase of computer usage. Music CDs often included music videos, wallpapers, and other various content. However, more recently, acts wishing to include enhanced content often include a DVD instead, with the advantage of it playing in both a computer's DVD-ROM drive and in a standard DVD player, and where the content is often in higher quality.
Sometimes computer CD-ripping programs (particularly cdparanoia) have problems ripping some enhanced CDs, especially those that have the data in a separate section after the audio section. These CDs have the data 11,400 sectors (2m32s) after the audio, but some CD rippers may try to rip this blank section with the last track; the end result is that the ripper stalls during the last track or simply reports errors.
See also 
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