This book is based on notes from a course on set theory and metric spaces taught by Edwin Spanier, and also incorporates with his permission numerous exercises from those notes. The volume includes an Appendix that helps bridge the gap between metric and topological spaces, a Selected Bibliography, and an Index.
I was looking for readings on Set Theory and found this as a suggestion on Stack Exchange. I'm currently working through the problems and this book is delightful. I would recommend this over the more popular Set Theory books such as Halmos. It is an easy read with interesting problems(you could do formal proofs for most of them if you wish to). The explanations are clear and concise.
Very clear and concise. The transition from set theory to metric spaces was done in a very clean manner. One of the better books I've read on the subject.