This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book provides the project description and data from field investigation and laboratory testing. It deals with the effects of geology on rock formation and common types of rock. The book discusses common rock exploration methods and techniques and presents discontinuities in rock mass. It describes rock properties and rock testing methods. The book shows practical applications of rock mechanics, including the assessment of rock mass properties, rock fall and landslide disaster, and common issues with rock mass during tunnel construction. Many engineering structures are built on rocks, while rocks are commonly used as construction material for several engineering applications. For this reason, engineers and researchers are required to have a sound knowledge of rock properties and understand the behavior of rock mass under stresses.