Geology is the study of the Earth, its materials, the structure of those materials, and the processes that affect them. It encompasses the study of species that have lived on our planet in the past. The study of how Earth's materials, structures, processes, and species have changed over time is an essential element of geology. We can learn about how the Earth has evolved over time by examining rocks, geochemistry, and geobiology. We can also predict how the planet will alter in the future. Modern geology is considered a major component of Earth system science and planetary science as a whole. People are at risk from a variety of processes, including landslides, earthquakes, floods, and volcanic eruptions. Geologists strive to have a thorough understanding of these processes so that major structures are not built in potentially hazardous areas. Geologists perform research to find important metal-bearing rocks, plan mines to generate them, and devise means to extract the metals from the rocks. They find and produce oil, natural gas, and groundwater in a similar way.