Corrosion is the process by which a metal deteriorates and decomposes due to a chemical reaction with its surrounding environment. There are different types of corrosion that can occur through various mechanisms depending on factors like temperature, moisture, and chemical composition. The document provides an overview of corrosion, its types and mechanisms, factors affecting corrosion, and examples like rusting of iron and the formation of a green film on copper. It concludes by thanking the reader and listing references used.