Drilling engineering is a multidisciplinary subject, including a broad spectrum of topics in engineering, geology, chemistry, and physics. The past 20 years have produced explosive growth in new technologies in the drilling industry; the basic approach to drilling engineering has also moved from "rules of thumb" and correlations to a more fundamental, physics-based science. This book takes a new look at the fundamental principles of drilling engineering. The book is essential for undergraduate and graduate students, as well as industry professionals trying to gain detailed knowledge of basic drilling concepts.