 information technology (IT) /Telecom experts and third-party suppliers can be found in a few topics, such as bitrate, interface, class of service, and network performance. If you don't understand it and can't communicate it, you risk being misunder- stood or, worse yet, mislead or taken advantage of. On the other hand, if you understand and can explain it, you can question and make sure your suppliers and colleagues understand. They might not agree, but that's another story. The material in this chapter lays a foundation for the remainder of the book. The three models, mentioned in the introduction-Program 1 BASIC FUNDAMENTALS, DEFINITIONS, AND KEY TERMS Content Food Chain, Network Interface Device (NID), and End-to-End Service-are defined and explained. All are current and relatively un- dated. However, it would be unrealistic not to expect features and functions of the NID and end-to-end service model to evolve over time. The food chain model should be stable and useful for a long time. CONTENT AND CONTENT TRANSPORT DEFINED Content, in simple terms, is information in the form of audio, video, still and moving images. Information from transducers, which monitor anything from pressure in a pipe to earthquake vibrations displayed on a Richter scale, could be deemed content. Content is sometimes confused with media. In the event confusion occurs, sort it out by thinking of the paper cup and string model. The sound traveling from one cup to the other is content and the string between the two serves as media. Think of the cups as the interface between the content and the media. Audio and video signals begin life in analog form. Audio is aperi- odic, unstructured, and reflective of the dynamic, random nature of sound. Once converted to digital, it takes on a rigid, blocky, periodic structure. Video is different. It is highly structured, reflecting the nature and character of a scan mechanism. The scanning mechanism supports organization of a frame of information coming from a relatively large group of individual sens