This book describes the basic concepts and principles of classical mechanics in the intermediate level. Given the perspective that different mechanical problems require an appropriate approach drawn from various methods or principles, a textbook discussing multiple methods or principles in mechanics is highly desirable. Additionally, a good textbook should include historical context on the motivation and the development of the methods or principles, allowing students to gain insights that may help them discover new theories. However, after many years of teaching Dynamics in the graduate school, the authors were unable to find a suitable intermediate-level textbook on classical mechanics, which motivated them to begin writing this book. For the aforementioned reasons, this book includes the descriptions of various methods or principles in mechanics, such as the Newton-Euler Principle, the d-Alembert Principle, Lagrangian methods, Gauss-s Principle of Least Constraint, the Gibbs-Appell e
