CD-i (Compact Disc - interactive) is the multimedia CD format specified in 1986 (in the Green Book). CD-i was specified as an entire system, comprising not just a disc and data format, but a hardware and software system, a variety of special compression methods for audio and visual data, and a method of interleaving audio, video, and text data. Developed as a user-friendly alternative to a PC, CD-I players are easier to use, and have TV video output as well. Full screen motion video capabilities were added to the original specification later.
A CD-i player is a stand-alone system that includes a CPU, memory, and an integrated operating system. It can be connected to a TV set for displaying pictures and sound, or to a stereo system. The user interacts by positioning a cursor and selecting options, with a device such as a specialized remote control.
Although CD-i never realized broad commercial success, it is now used in education, training, and other professional applications.