Explore the foundational principles and practical applications of information theory with "Theory of Information and its Value" by Ruslan L. Stratonovich. This English hardcover edition, first published in 2020, delves into the unification of information theory, optimization, and statistical physics, making it increasingly relevant in today's data-driven world. Written by Roman V. Belavkin, Panos M. Pardalos, and Jose C. Principe, this book extends the classic work of R.L. Stratonovich, a pioneer in stochastic calculus and filtering theory. Each chapter begins with fundamental concepts and clear examples, progressively advancing to detailed and in-depth material. This comprehensive guide is accessible to a wide audience, including researchers, postgraduates, and undergraduate students in mathematics, engineering, physics, and computer science specializing in information theory, data analysis, or machine learning. It features 29 black and white illustrations and 4 color illustrations, totaling 419 pages. **Summary:** Springer Nature Switzerland AG, Theory of Information and its Value, Hardcover book, English, 419 pages, First edition, ISBN 9783030228323.