The Course of Variational Calculus is an outstanding work written by Mikhail A. Lavrentiev, one of the most famous Soviet mathematicians and mechanics. This book is not just a textbook, but a real encyclopedia of variational calculus, which opens the world of mathematical concepts and their practical application to the reader. Variational calculus is a field of mathematics that searches for extremities of functionals, and in this work Lavrentiev masterfully explains complex ideas, making them available to a wide range of readers. The book covers both theoretical aspects and practical problems, making it an indispensable tool for students, graduate students and teachers, as well as for anyone interested in mathematics and its applications in physics, engineering and other sciences. Lavrentiev, possessing a unique style of presentation, skillfully combines rigor and intuition, which allows the reader not only to assimilate the material, but also to feel its beauty and elegance. His approach to explaining complex concepts makes the book particularly attractive to those seeking a deeper understanding of calculus. Readers familiar with his other works, such as "Basics of Mathematical Control Theory" or "Methods of Mathematical Physics", will find in this work the familiar style and depth of analysis. The book "Course of Variational Calculus" will be of interest not only to students of mathematical and physical faculties, but also to practicing engineers, economists and everyone who is faced with optimization tasks. It can become a reference book for those who work in the field of control theory, mechanics, as well as in related disciplines, where the application of mathematical methods to solve real problems is required. The topics raised in the book cover a wide range of issues, from the basics of variational calculus to more complex concepts such as functionals, variational equations, and methods of solving them. Lavrentiev not only explains the theory, but also gives many examples, which allows the reader to see the practical application of the methods studied. This makes the book especially valuable for those who want not only to learn the theory, but also to learn how to apply it in practice. In addition, The Course of Variational Calculus raises important philosophical questions about the nature of mathematics and its role in understanding the world around it. Lavrentiev, as a true scientist, is not afraid to ask questions and seek answers, which makes his book not only a textbook, but also a source of inspiration for reflection. If you are looking for a book that will help you immerse yourself in the world of calculus, expand your knowledge and skills, then the “Course of calculus of variations” by Mikhail Alekseevich Lavrentiev is exactly what you need. This book will be your reliable companion in the study of one of the most fascinating and important areas of mathematics, opening up new horizons and opportunities for you. Do not miss the chance to get acquainted with the work of the great mathematician and discover the amazing world of calculus!