What is pasteurization?
Invented by a French scientist Louis Pasteur, pasteurization got it’s name from his last name. It is the process of heating and then rapidly cooling - liquids or food. This is done to kill microbes that may cause diseases or speedup the spoilage.
Milk is often pasteurized because cattle can get mastitis, a condition which is inflammation of the udder which causes infection. This caused by the bacteria can be dangerous to human beings as well if they drink raw (unpasteurized) milk. This is why pasteurization is used in milk and other such products.