Butter is made from milk coming from a variety of different animals, from cows to goats and even yaks. Milk from the animal of choice is taken and churned to separate out the fatty parts from the liquids. The left over liquid is removed and is a substance known as buttermilk that has it's own uses. After the buttermilk is removed the fatty leftovers undergo a process of kneading that forms the substance together. This is when the substance becomes butter. However even though the butter is now done, there are several other steps that it undergoes before reaching a store. The butter is generally mixed with a some form of seasoning, most commonly light salt to improve the flavor. The butter must also be pasteurized in order to prevent the spread of bacteria.