CDS is an Audio CD copy protection scheme developed by the Israeli company Midbar Tech (www.midbartech.com). CDS is already being used on several newly released CDs. So far there are two different types:

CDS100
This method works by inserting errors into the TOC, thus confusing CD-ROM drives, preventing them from playing the tracks and ripping them to the hard drive.

CD-ripping programs have already found a way around this, like EAC which manually analyses the whole CD without having to read the TOC. Also, Plextor drives seem to have no problems with this form of copy protection.

CDS200
Essentially the same as CDS100, CDS200 lets you play the CD on your computer by adding a data track to the CD which holds the tracks in MP3 format and opens them in an included software player which then plays them. Supposedly the files are copy-proof and can not be transferred to the hard drive.

There have been rumours of people sticking a piece of a Post-It over the data track, effectively disabling the protection.

lj tells me that there is also the method of drawing a line with a black marker across the data area. This is just as effective, the only problem is that your CD looks like crap afterwards.