Corrosion: It is a process of slow and gradual conversion of a metal into its undesirable compounds (sulphides, carbonates, oxides, etc.) by the attack of air and moisture (water) present in the atmosphere.
For example,reddish brown coating on iron, black coating on silver and green coating on copper are some examples of corrosion of iron, silver and copper respectively. Corrosion of iron is known as rusting.
