The process of converting a solid directly into a gas is called sublimation. This phenomenon occurs when a solid transitions to a gaseous state without first becoming a liquid, typically under specific temperature and pressure conditions. Common examples of sublimation include dry ice (solid carbon dioxide) turning into carbon dioxide gas and the transformation of snow or ice into water vapor in sub-zero environments. Sublimation is an endothermic process that requires energy to break the intermolecular bonds of the solid, allowing the particles to escape into the air as gas. It is an essential concept in physical chemistry and material science.