One Click Butter Cutter
From the Wisconsin Dairy web site,

Q: What is the definition of butter?

A: Butter is a food product, which is made exclusively from milk, cream or both, with or without common salt, and containing at least 80 percent milk fat by weight.

Q: How many different types of butter are available in the U.S?

A: There are two main types of butter produced in the U.S. Ė sweet cream butter and cultured cream butter. The United States primarily produces sweet cream butter, which includes lightly salted, unsalted and whipped butter.

Lightly salted butter is the perfect ingredient for general cooking.
Unsalted butter is great for baking, creating flaky crusts and sweet treats with great taste and texture. Both lightly salted and unsalted butter are available in sticks for easy measuring when cooking or baking.
Whipped butter is whipped with air to make it light and fluffy and comes in tubs, making it an ideal table spread.
Cultured butter, a rich butter made from cultured cream, is popular in Europe and is now being produced in the U.S. It is available in most regions of the country. As with lightly salted and unsalted butter, itís available in both sticks and tubs.

Q: Whatís the difference between salted and unsalted butter?

A: Salt acts as a preservative and adds flavor to butter. Lightly salted butter is sometimes called "sweet cream butter," and is best used as a table butter and for general cooking needs. Unsalted butter, too, is "sweet butter," but is used mainly for baking. Although unsalted and salted butter may be specifically recommended for cooking or baking particular items, they can generally be substituted for one another.

Q: Whatís the difference between butter and margarine?

A: Butter is a natural dairy product made by churning or shaking cream until it reaches a semisolid state. Margarine is made from a single oil, or blend of oils, including animal and vegetable fats.

Because butter is a natural product, its performance in cooking and baking is unduplicated, naturally enhancing food flavor and providing a creamy texture.