The book “Classification of Equations and Characteristics”, written by a team of authors, is a fascinating and in-depth study in the field of mathematical theory of equations .. This publication will be an indispensable assistant for students, graduate students and teachers, as well as for anyone interested in mathematics and its applications in various fields of science and technology. The book focuses on the classification of equations, which is a key aspect in understanding their properties and behavior. The authors offer the reader a unique approach to the analysis of equations, which allows not only to systematize knowledge, but also to deepen understanding of mathematical concepts. Each equation, whether linear, nonlinear, ordinary or particular, is considered through the prism of its characteristics, which makes the book especially valuable for those who seek a deeper understanding of the subject. The book will be of interest to both senior students and those who already have experience in mathematics and want to expand their horizons. It will be useful to those who study physics, engineering, economics and other sciences, where equations play a central role. Readers interested in the theory of differential equations, mathematical modeling and numerical methods will find in this edition many useful ideas and approaches. The topics raised in the book cover a wide range of issues. The authors investigate not only the classification of equations, but also their application in real problems, which makes the material especially relevant. The book discusses the methods of solving equations, their properties and features, as well as the influence of various parameters on the behavior of decisions. This allows the reader not only to learn the theoretical aspects, but also to apply them in practice. The style of the authors is distinguished by clarity and accessibility, which makes complex mathematical concepts understandable even for beginners. Each section of the book is accompanied by examples and tasks, which contributes to a better assimilation of the material .. In addition, the team of authors includes specialists with different scientific interests, which gives the book a multifaceted and diverse approach. If you are looking for books that will help you deepen your knowledge in the field of mathematics, pay attention to such works as "Differential Equations" H. N. Bogolyubov