This volume presents a lively introduction to the rapidly developing and vast research areas surrounding Calabi-Yau varieties and string theory. With its coverage of the various perspectives of a wide area of topics such as Hodge theory, Gross-Siebert program, moduli problems, toric approach, and arithmetic aspects, the book gives a comprehensive overview of the current streams of mathematical research in the area.The contributions in this book are based on lectures that took place during workshops with the following thematic titles: "Modular Forms Around String Theory," "Enumerative Geometry and Calabi-Yau Varieties," "Physics Around Mirror Symmetry," "Hodge Theory in String Theory."  The book is ideal for graduate students and researchers learning about Calabi-Yau varieties as well as physics students and string theorists who wish to learn the mathematics behind these varieties.