List of book recommendations

For the [reasons explained here](https://buddhism.meta.stackexchange.com/q/2248/254) , can you recommend one or more books about Buddhism? - I suggest a format like, > Title of Book by Name of Author > A summary of what's in the book, recommended for these reasons. - One book per answer (but multiple answers, a different book for each answer, is welcome) - Books -- but not videos -- i.e. readable; published in print, and/or online - I think it's more important to mention why you recommend a book, and less important to summarise what's in it --- Unlike most other topics on this site, this topic is [Community Wiki](https://meta.stackexchange.com/a/11741/139866) . If it's a good *introductory* book then post it here instead -- https://buddhism.stackexchange.com/q/60/254 -- and use this topic for other (non-Introductory) books about any more-specific topics.