This book provides a comprehensive introduction to the digital transmission chain, covering the fundamental principles, theoretical foundations, and practical aspects of digital communication systems. It guides the reader from the information source through Source Encoding, Channel Encoding, Digital Modulation, Transmission Channel and Reception and Decoding up to the final recipient. The content balances theory with practice, including illustrative examples and case studies on modern communication systems such as FTTH, 4G, and 5G. Designed for undergraduate and graduate students in telecommunications and computer science, as well as engineers and researchers, the book offers a clear and structured approach to understanding both the components and performance of digital transmission systems.