Julia E. Bergner is an Associate Professor at the University of Virginia. She has written several foundational papers in the area of (¿, 1)-categories, and is currently working on generalizations to higher (¿, n)-categories, (¿, 1)-operads, and equivariant versions. She currently has an NSF CAREER award to investigate algebraic and geometric applications of these kinds of structures. This book was inspired by the notes from a series of lectures on 'The Homotopy Theory of Homotopy Theories' presented in Israel in 2010, with talks given by the author and a number of other participants.