The book is very well organized and the structure of each chapter is helpful: notation, assumptions, statements, examples, proofs and comments are clearly separated. this makes the book a good reference for researchers interested in rare event analysis and approximation. (Charles-Edouard Bréhier, Mathematical Reviews, August, 2020) The current book requires a solid background in weak convergence of probability measures and stochastic analysis, and it is intended for advanced graduate students, post-doctoral fellows and researchers working in this area. (Anatoliy Swishchuk, zbMATH 1427.60003, 2020)