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 animal on the cover of Mastering Algorithms with Perl is a wolf (Canis lupus). The wolf, a member of the dog family, is one of the most sociable of mammals. Wolves live and hunt in packs, which consist of one pair of alpha male and female wolves and several offspring. Pack size is usually five to nine wolves. Each wolf pack has its own territory, which they will mark and fight to defend. Wolves often travel long distance in their hunt for prey, and they keep in contact with other members of their pack by howling. Howling seems to be almost contagious to wolves-when one wolf begins to howl, others around it will almost always join in, creating an echoing, almost musical effect. Wolves were once common throughout the northern hemisphere. Deserts and tropical forests are the only habitats that cannot support wolves. However, as a result of disease, parasites, starvation caused by habitat loss, and persecution by humans, wolves have been eradicated from much of their former territory and are limited in others. Significant wolf populations are now found only in Canada, Alaska, Minnesota, and parts of Asia. Smaller wolf populations can be found in Scandinavia and parts of Europe. In Greenland, the wolf was nearly extinct, but has managed to repopulate itself. The grey wolf is currently listed as vulnerable. The relationship between wolves and humans has always been a troubled one. Folktales and childrens' stories have long characterized the wolf as an evil, bloodthirsty killer who preys on children and other humans. In fact, healthy wolves rarely, if ever, attack humans. On a more down-to-earth level, farmers resent wolves because they frequently kill livestock. However, wolves provide a beneficial service: they feed on carrion, rodents, and other pests. Because of their greatly diminished numbers, wolves have come to symbolize to many the disappearing wilderness. Interest in preserving them is growing as a result. Melanie Wang was the production editor and copy editor for Mastering Algorithms with Perl; Ellie Cutler, Maureen Dempsey, Abigail Myers, Colleen Gorman, and Jane Ellin provided quality control. Kimo Carter provided production support. Lenny Muellner provided technical support. Seth Maislin wrote the index, with additional index work done by Ellen Troutman Zaig and Brenda Miller. Edie Freedman designed the cover of this book, using an original illustration by Lorrie LeJeune. The cover layout was produced by Kathleen Wilson with QuarkXPress 3.32 using the ITC Garamond font. Whenever possible, our books use RepKover, a durable and flexible lay-flat binding. If the page count exceeds RepKover's limit, perfect binding is used. The inside layout was designed by Alicia Cech based on a series design by Nancy Priest and implemented in gtroff by Lenny Muellner. The text and heading fonts are ITC Garamond Light and Garamond Book. The illustrations that appear in the book were produced by Robert Romano and Rhon Porter using Macromedia FreeHand 8 and Adobe Photoshop 5. This colophon was written by Clairemarie Fisher O'Leary.