Soft serve ice cream

Soft serve, also known as soft ice, is a frozen dessert and variety of ice cream, similar to conventional ice cream, but softer and less dense due to more air being introduced during freezing. Soft serve has been sold commercially since the late 1930s in the United States. In the United States, soft serve is not typically sold prepackaged in supermarkets but is common at fairs, carnivals, amusement parks, restaurants , and specialty shops. All ice cream must be frozen quickly to avoid crystal growth. With soft serve, this is accomplished by a special machine that holds pre-mixed product at a very low, but not frozen, temperature at the point of sale.

Source: Wikipedia