ts, files, images, and videos. The description is just meant to be introductory and makes no pretense of comprehensively defining the actual standards and their current updated versions. The list of selected standards is also indicative, and does not reflect the full diversity of those available in the market, as freeware, shareware, or under license. It is a tricky endeavor to attempt a description here in a few pages of a subject that would fill entire bookshelves. The hope is that the reader will get a flavor and will be enticed to learn more about this seemingly endless, yet fascinating subject. Why put this whole matter into an appendix, and not a fully fledged chapter? This is because this set of chapters is primarily focused on information theory, not on information standards. While the first provides a universal and slowly evolving background reference, like science, the second represents practically all the reverse. As we shall see through this appendix, however, information standards are extremely sophisticated and "intellectually smart," despite being just an application field for the former. And there are no telecom engineers or scientists who may ignore or will not benefit from this essential fact and truth! Sounds Speech is historically the first type of information that has been subject to coding and compression. The need for speech coding has first come from the development of telephony, with the introduction of digitally sampled voice progressively replacing the old analog telephone service. The benefits of digital voice are essentially twofold: (a) a better sound quality for the users, perceived as free from background noise and interference, and (b) owing to the high fidelity of the transmission, and in particular to error-correction coding, the possibility for the telephone operator to compress and multiplex together several voice channels in the same time slot (referenced to as time- division multiplexing, or TDM). But there are even more important benefits for the telephone operator, for man