The book "Fundamentals of the theory of spectra of atoms and ions" by Alexei Alekseevich Nikitin and Zenonas Bronislavovich Rudzikas is a unique and in-depth study in the field of atomic physics and spectroscopy. This work will be an indispensable tool for both students and professionals interested in the physics of atoms, their interaction with radiation and spectral characteristics. In this book, the authors examine in detail the foundations of spectrum theory, starting with elementary concepts and ending with complex mathematical models. They seek to explain how atomic and ion spectra form and how they can be used to study various physical phenomena. Each section of the book is filled with clear explanations and examples, which makes the material understandable even for those who are just starting their way in the study of physics. Who can like this work? First of all, the book will be of interest to physics students, graduate students and teachers, as well as everyone who is fond of scientific research in the field of atomic and molecular physics . If you are looking for a deep understanding of spectroscopy and want to know how different atoms and ions interact with electromagnetic radiation, this book will be a real discovery for you. The topics raised in the book cover a wide range of issues, including quantum mechanics, the interaction of light and matter, and the application of spectroscopy in various fields of science. The authors emphasize the importance of the theoretical foundations that underlie the practical application of spectroscopy in fields such as astronomy, chemistry, and materials science. They highlight how understanding spectra can help solve pressing problems, such as analyzing the chemical composition of stars or exploring new materials. The style of the authors is distinguished by clarity and logical presentation, which makes complex concepts more accessible for understanding. Alexey Alekseevich Nikitin and Zenonas Bronislavovich Rudzikas are experienced scientists who are not only engaged in research activities themselves, but also actively participate in the educational process. Their previous work is also devoted to the physics of atoms and ions, and they can find many interesting ideas and approaches that the authors apply in this book. The book "Fundamentals of the theory of spectra of atoms and ions" is not just a textbook, but a real encyclopedia of knowledge that will help readers not only to master the theoretical aspects, but also to see the practical application of the knowledge gained. If you are looking for materials on spectroscopy, quantum mechanics or atomic physics, this book will be a great addition to your library. Thus, if you want to deepen your knowledge of spectrum theory and understand how this knowledge can be applied in real scientific research, don’t miss the opportunity to get acquainted with this outstanding work. The book promises to be an important step towards understanding the complex and fascinating processes occurring in the world of atoms and ions.