Arnold's Problems contains mathematical problems which have been brought up by Vladimir Arnold in his famous seminar at Moscow State University over several decades. In addition, there are problems published in his numerous papers and books. The invariable peculiarity of these problems was that mathematics was considered not as a game with deductive reasonings and symbols, but as a part of natural science (especially of physics), i.e. as an experimental science. Many of these problems are at the frontier of research still today and are still open, and even those that are mainly solved keep stimulating new research appearing every year in journals all over the world. The second part of the book is a collection of comments of mostly Arnold's former students about the current progress in the problems' solution (featuring bibliography inspired by them). This book will be of great interest to researchers and graduate students in mathematics and mathematical physics.