How Do Cows Make Milk?

My question is, how do cows make milk? First, for a cow to make milk, she has to have a baby. Each cow can make between four and eight gallons of milk each day. Most milk is processed by doing something called pasteurization which heats it up really quickly to kill bacteria before cooling the milk back down again very quickly. Unless you drink something called raw milk, your milk has been pasteurized.