corrosion is the breakdown of materials due to chemical reactions. it is usually oxidation with air molecules and often in the presence of water. corrosion also occurs when an acidic/basic corrosive substance touches another material. when a material corrodes, its physical properties change. problems with corrosion are mostly with metal, though other materials can corrode. corrosion is a form of erosion. some materials, such as stainless steel, are highly resistant to corrosion. metals that may corrode can be protected by plating, painting, and other means.