What is information? How can it be represented, securely transmitted, or stored? Many questions to which the book provides answers. Information theory lays the foundation for calculating the information content of discrete and continuous sources and their representation in coded form. This allows for determining the necessary storage and channel capacities in information processing and transmission within IT systems. Sections in the channel coding chapter have been restructured and expanded. It presents solutions for secure information transmission over disturbed channels. Detailed descriptions of block and block-free codes, serial and parallel code concatenations with hard decision and (iterative) soft decision decoding are provided, which serve for error detection and correction. The content covers information sources and their description - coding of discrete sources.