Optical waveguide theory is a comprehensive text by Allan W. Snyder and John D. Love, covering both ray and electromagnetic analysis of optical waveguides. The book is divided into three parts: Part I focuses on ray analysis of multimode waveguides, Part II on electromagnetic analysis, and Part III on supplementary mathematical methods. The authors emphasize physical concepts alongside mathematical analysis, providing a self-contained treatment of the subject. The text includes over 150 problems with solutions to illustrate applications of the theory. It is designed to be accessible to undergraduates, with a focus on simplicity and clarity. The book presents fundamental topics for the first time and unifies basic ideas using the simplest approach possible. The material is organized logically, with recommendations for reading specific chapters depending on the course objectives. The authors acknowledge the contributions of colleagues, students, and staff who helped in the development and publication of the book. The text is intended to provide a thorough understanding of optical waveguide theory, with a balance between physical intuition and mathematical rigor. It is suitable for both students and researchers in the field of optical engineering and physics.Optical waveguide theory is a comprehensive text by Allan W. Snyder and John D. Love, covering both ray and electromagnetic analysis of optical waveguides. The book is divided into three parts: Part I focuses on ray analysis of multimode waveguides, Part II on electromagnetic analysis, and Part III on supplementary mathematical methods. The authors emphasize physical concepts alongside mathematical analysis, providing a self-contained treatment of the subject. The text includes over 150 problems with solutions to illustrate applications of the theory. It is designed to be accessible to undergraduates, with a focus on simplicity and clarity. The book presents fundamental topics for the first time and unifies basic ideas using the simplest approach possible. The material is organized logically, with recommendations for reading specific chapters depending on the course objectives. The authors acknowledge the contributions of colleagues, students, and staff who helped in the development and publication of the book. The text is intended to provide a thorough understanding of optical waveguide theory, with a balance between physical intuition and mathematical rigor. It is suitable for both students and researchers in the field of optical engineering and physics.