Weathering is a fundamental geological process involving the breakdown and chemical alteration of rocks, soils, and minerals at or near the Earth's surface. It is broadly categorized into physical (or mechanical) weathering, which reduces rocks to smaller fragments without altering their chemical makeup—a common example being exfoliation or the expansion and contraction caused by temperature change. Chemical weathering involves chemical reactions that decompose the rock material, such as oxidation, hydrolysis, and carbonation, where chemical compounds in the atmosphere or water react with the mineral structure. Together, these processes are responsible for shaping the planet's topography, contributing vast amounts of sediment, and forming the essential mineral components of soil.