Our look is the result of reader comments, our own experimentation, and feedback from distribution channels. Distinctive covers complement our distinctive approach to technical topics, breathing personality and life into potentially dry subjects.

The animals on the cover of Upgrading to PHP 5 are Galapagos tortoises (Geochelone elephantopus). These giant tortoises, native to the Galapagos Islands, are the largest in the world. They can weigh up to 500 pounds and measure up to 6 feet from head to tail. As their bulk suggests, they are slow-moving animals, with a top speed of 0.16 mph. Their plodding pace applies to more than just their gait-they can live for 200 years and take 20 to 25 years to reach full maturity. Baby tortoises spend a full month digging out of their sandy nests after they hatch.

Galapagos tortoises are herbivores, and their strong, curved mouths allow them to eat the spiny vegetation found on the more arid islands in the Galapagos chain. Their slow metabolism allows them to survive for long periods of time without food or water, which is necessary during the dry season. Their scaly feet help them navigate the islands' rough lava terrain.

Fifteen subspecies of Geochelone elephantopus have been found in the Galapagos Islands, an archipelago located about 600 miles off the coast of Ecuador. The different subspecies are identified primarily by their shell morphology: saddle-back and domed shells are the two general types, but there are intermediate variations. The subspecies descend from a common ancestor, but developed their unique characteristics in response to the varied terrain, available food, humidity, and other environmental factors found on the islands. Charles Darwin's observations of Galapagos tortoises and how they adapted to their environments helped him formulate his theory of natural selection.

Galapagos tortoises are endangered, and several subspecies are already extinct. Before whalers, seal fur hunters, and colonists arrived in the 18th century, about 250,000 tortoises lived on the islands. Today, only 15,000 remain.

Genevieve d'Entremont was the production editor and copyeditor for Upgrading to PHP 5. Sada Preisch proofread the book. Sarah Sherman and Claire Cloutier provided quality control. Angela Howard wrote the index.

Ellie Volckhausen designed the cover of this book, based on a series design by Edie Freedman. The cover image is a 19th-century engraving from the Dover Pictorial Archive. Emma Colby produced the cover layout with QuarkXPress 4.1 using Adobe's ITC Garamond font.

Melanie Wang designed the interior layout, based on a series design by David Futato. This book was converted by Joe Wizda to FrameMaker 5.5.6 with a format conversion tool created by Erik Ray, Jason McIntosh, Neil Walls, and Mike Sierra that uses Perl and XML technologies. The text font is Linotype Birka; the heading font is Adobe Myriad Condensed; and the code font is LucasFont's TheSans Mono Condensed. The illustrations that appear in the book were produced by Robert Romano and Jessamyn Read using Macromedia FreeHand 9 and Adobe Photoshop 6. The tip and warning icons were drawn by Christopher Bing. This colophon was written by Genevieve d'Entremont.

The online edition of this book was created by the Safari production group (John Chodacki, Becki Maisch, and Ellie Cutler) using a set of Frame-to-XML conversion and cleanup tools written and maintained by Erik Ray, Benn Salter, John Chodacki, Ellie Cutler, and Jeff Liggett.