The Whole Internet Catalog & User's Guide by Ed Krol (O'Reilly Media publisher) was the first comprehensive user guide to the Internet. This book sold over 1,000,000 copies and was named one of 100 Books of the 20th Century by the New York Public Library. Although markedly dated, indeed some of the services discussed are no longer in general use and some of the services available today weren't around at the time it was written to be discussed, it remains an enormously important work and is a great way for the serious student of the Internet to get a solid grounding in the underlying foundation of this thing we use every day. Read it in public document format (PDF) format -- it's a large file, 36MB, so it will take a while to open -- or purchase a copy on Amazon with the links on the previous page.