Dairy Queen is a fast food chain founded 1940 in Joliet, Illinois. It sells hamburgers, hot dogs, french fries, soft-serve ice cream, ice cream bars, and milkshakes. It is also well known for originally making the Blizzard treat and also currently sells ice cream cakes.
In the U.S., the Oreo variety of Blizzard is most popular. In China, the most popular is Green Tea. Their exact recipe is a closely-guarded trade secret, which they believe makes their 5% butterfat soft-serve "queen among dairy products," as Jack McCullough said.