This document provides an overview of geology as a science. It discusses how geology studies the composition, structure, and evolution of the Earth over geological time. It notes that geology encompasses various geological sciences and provides essential insights into plate tectonics, the history of life through paleontology, past climates, and more. Geology also has important applications in fields like mining, petroleum extraction, hydrogeology, natural hazard prevention, and environmental protection. The document outlines some of the major branches and areas of study within geology.