Butter is a dairy product made by churning fresh or fermented cream or milk. Butter is used as a spread and a condiment, as well as in cooking applications such as baking, sauce making, and frying. Butter consists of butterfat surrounding minuscule droplets consisting mostly of water and milk proteins. The most common form of butter is made from cows' milk, but it can also be made from the milk of other mammals, including sheep, goats, buffalo, and yaks. Salt, flavorings, or preservatives are sometimes added to butter. Rendering butter produces clarified butter or ghee, which is almost entirely butterfat. When refrigerated, butter remains a solid, but softens to a spreadable consistency at room temperature.
Do not use 'spreads' in place of butter. Most spreads contain very high amounts of water and are therefore not suitable for culinary use. If you don't have butter, use olive oil.