This document provides information about downloading the book "Animal Physiology" by Richard W. Hill for free online. It is an 828 page book published by Sinauer Associates, covering all branches of modern animal physiology with a strong emphasis on integration of physiological knowledge, ecology, and evolutionary biology. The book takes a comparative approach and focuses on understanding whole animals in their environments. It includes illustrations, study questions, and appendices to aid student learning. Resources for both students and instructors are provided on a companion website, including chapter outlines, figures from the book, and test questions.