On 8 March 1979, N.V. Philips' Gloeilampenfabrieken demonstrated for the international press a Compact Disc Audio Player. The demonstration showed that it is possible by using digital optical recording and playback to reproduce audio signals with superb stereo quality. This research at Philips established the technical standard for digital optical recording systems. This event marked the start of the worldwide development of consumer digital optical recording and reproduction equipment, obtainable by the peoples of the world for a low price. Originally designed for quality audio conservation and reproduction, it fanned out to the world of multi media and the personal computer. In short this demonstration stood at the root of the family tree of CD, CD-ROM, DVD etc. Technologically it was an example of multi disciplinary research: the mastering of the problems of solid state lasers, optical system including focusing, D/A and A/D converters, digital coding and error correction, modulation system, servo system for track following and envisioned mass production of the recorded media. The social and industrial impact of this milestone can be measured by the number of spin-offs and industries now active in this field. Furthermore the public acceptance was evident: the CD completely replaced the gramophone record and player in a very short time. The broadness of scope, foresight and vision of this research and development activity of Philips, as indicated above, was well received in the technical world. It resulted in a multitude of publications. The status of this work can be measured by the willingness of Sony, as early as March 23, 1979, to develop the system further together with Philips. This resulted in the worldwide standardization of the CD system, a remarkable feat in the very competitive field of consumer electronics. The impact caused on the community and technology can not be underestimated. The Milestone plaque is located at the High Tech Campus Eindhoven, the Netherlands, Open Section of the Information Services. Philips Research is situated on this Campus, together with other electronics enterprises.