Eggnog, historically also known as a milk punch or an egg milk punch when alcoholic beverages are added, is a rich, chilled, sweetened, dairy-based beverage. It is traditionally made with milk, cream, sugar, egg yolks, and whipped egg whites. A distilled spirit such as brandy, rum, whiskey or bourbon is often a key ingredient.

Cream is a dairy product composed of the higher-fat layer skimmed from the top of milk before homogenization. In un-homogenized milk, the fat, which is less dense, eventually rises to the top. In the industrial production of cream, this process is accelerated by using centrifuges called "separators". In many countries, it is sold in several grades depending on the total butterfat content. It can be dried to a powder for shipment to distant markets, and contains high levels of saturated fat.