Butter Varieties

When baking, it is really important to use unsalted butter because the amount of the salt in the recipe needs to be carefully controlled: it is usually there more for it's chemical properties (such as aiding in leavening) than for flavor.

When cooking savory foods, butter is often used as a cooking medium (to prevent food from sticking to the pan or to enhance browning, for example) or to enrich a sauce. Using unsalted butter allows you to decide where, when, and how much salt to add to the dish for flavor.

Salted butter is ideal for spreading on bread, crackers, sandwiches, etc. That is, when you are eating butter for butter's sake, and not for the properties it will add to your cooked food.