The process by which a solid turns directly into a gas is called sublimation. This phase transition occurs without passing through the liquid state. Common examples include dry ice (solid carbon dioxide) evaporating into gas and snow disappearing in cold, dry conditions. Sublimation occurs under specific temperature and pressure conditions, typically when the solid's vapor pressure exceeds atmospheric pressure. Understanding sublimation is important in fields like chemistry, material science, and environmental science, as it has applications ranging from freeze-drying to understanding atmospheric processes.