This text is a light technical introduction to the three technical foundations for multimedia applications across the Internet: communications (principles, technologies and networking), compressive encoding of digital media, and Internet protocol and services. All the contributing systems elements are explained through descriptive text and numerous illustrative figures; the result is a book pitched toward non-specialists, preferably with technical background, who want descriptive tutorial introductions to the three foundation areas. The text discusses advances in digital audio/video coding, optical and wireless communications technologies, high-speed access networks, and IP-based media streaming, all crucial enablers of the multimedia Internet.