CD-i - (CD - Interactive) - Developed jointly by Sony Corporation and Philips International to store audio, video and binary data on compact optical disks. It can store up to 552 megabytes of binary data and has several different types of video and audio encoding formats. Unlike the conventional CD-ROM drive in your PC, CD-I machines have a built in microprocessor to handle many of computing functions. CD-I machines are often cheaper than personal computers and can have many applications. It's often (or was often) used for training purposes. Unfortunately CD-I programs are often more complicated to develop than other CDs due to the lack of standardized authoring tools, as well as the need for expert programming skills. Still CD-I products are often of higher quality than many CDs.
  
Promoted by CD-Online, an attempt was made to sell a modem plug-in for the CD-I machine. This would make it into an Internet terminal. Unfortunately it was largely a failure. The PC had overtaken the market and hardly anyone had CD-I players.  www.cdrfaq.org