Why's (poignant) Guide to Ruby
why's (poignant) Guide to Ruby, sometimes called w(p)GtR or just "the poignant guide", is an introductory book to the Ruby programming language, written by why the lucky stiff. The book is distributed under the Creative Commons Attribution-ShareAlike license. The book is unusual among programming books in that it includes much strange humor and many narrative side tracks which are sometimes completely unrelated to the topic. Many motifs have become inside jokes in the Ruby community, such as references to the words "chunky bacon". The book includes many characters which have become popular as well, particularly the cartoon foxes and Trady Blix, a large black feline friend of why's, who acts as a guide to the foxes (and occasionally teaches them some Ruby). The book is published in HTML and PDF. Chapter three was reprinted in The Best Software Writing I: Selected and Introduced by Joel Spolsky (Apress, 2005). Contents 
 About this book
 Kon'nichi wa, Ruby
 A Quick (and Hopefully Painless) Ride Through Ruby (with Cartoon Foxes): basic introduction to central Ruby concepts
 Floating Little Leaves of Code: evaluation and values, hashes and lists
 Them What Make the Rules and Them What Live the Dream: case/when, while/until, variable scope, blocks, methods, class definitions, class attributes, objects, modules, introspection in IRB, dup, self,  module
 Downtown: metaprogramming, regular expressions
 When You Wish Upon a Beard: send method, new methods in existing classes

The following chapters are "Expansion Packs":

 The Tiger's Vest (with a Basic Introduction to IRB): discusses IRB, the interactive Ruby interpreter. External links 
 Original Site
 Actively maintained fork
 3rd-party PDF version: Ruby Inside

Computer programming books
Creative Commons-licensed books
Ruby (programming language)
Books about free software