Programming Perl, best known as the Camel Book among programmers, is a book about writing programs using the Perl programming language, revised as several editions (1991-2012) to reflect major language changes since Perl version 4. Editions have been co-written by the creator of Perl, Larry Wall, along with Randal L. Schwartz, then Tom Christiansen and then Jon Orwant. Published by O'Reilly Media, the book is considered the canonical reference work for Perl programmers. With over 1,000 pages, the various editions contain complete descriptions of each Perl language version and its interpreter. Examples range from trivial code snippets to the highly complex expressions for which Perl is widely known. The camel book editions are also noted for being written in an approachable and humorous style.