Graph minor theory is one of the most influential and well-developed areas of graph theory, yet its key results, particularly the work of Robertson and Seymour, have remained scattered across numerous technical papers. This book fills an important gap by providing a comprehensive, structured treatment of the subject.  Divided into three main parts, the book first introduces the fundamentals of graph minor theory, focusing on the deep and powerful Minor Structure Theorem. It offers a clear roadmap for understanding the theorem’s proof, presenting its key ingredients while omitting only the most technical details. The second part explores a variety of applications, from algorithmic results to connections with the Linear Hadwiger Conjecture and graph coloring problems. The final section presents alternative approaches to graph minor theory that do not rely on the Minor Structure Theorem, covering topics such as sublinear separators, density, and isomorphism testing.  The exposition is rigorous yet accessible, striving to balance depth with readability. While some parts remain dense due to the complexity of the subject, the author provides valuable insights and explanations that make challenging concepts more approachable. The book not only serves as an excellent learning resource for graduate students and researchers entering the field but also as a long-lasting reference for experts.