Arborio rice is the most widely available variety of Italian superfino rice, used to make risotto. It has plump grains and a high proportion of amylopectin, a type of sticky starch that's responsible for the trademark creamy texture of risotto.
Arborio is a medium-grain rice (though it's often called short-grain rice because its plump shape after cooking makes it look short).
Substitute carnaroli or vialone nano rice.
Imported varieties are your best bet; to know you’re buying the real deal, look for a seal from the Italian rice growers’ consortium (it has a stork on it). If you’re buying the rice in bulk or you can see it through the bag, make sure the rice is for the most part intact; too many broken grains and the rice won’t cook evenly.
You can cook risotto ahead: Follow the recipe until the rice is about halfway done—it should still be rather firm inside—and then spread it out on a baking sheet to stop cooking. Cool the rice, then cover it and set it aside at room temperature for up to two hours. When you’re ready to serve the risotto, return it to the pot and resume adding hot liquid until it’s perfectly al dente, a few minutes later.
Store Arborio in a cool, dry place where it will keep well almost indefinitely.