Sultanas are the fruit and plant of Vitis vinifera. This variety of green, seedless, grape, usually sold dried, of ancient (possibly Persian) lineage, is often used in cooking especially in Australia and the United Kingdom.
They can be eaten as-is or used in baking. For some recipes, they are soaked in a liquid (fruit juice, alcohol, stock, or water), making them plump, tender and juicy. They are similar, though not identical, to the golden raisins sold in North America, and the two can be substituted for each other in recipes without disadvantage.
Normally it takes up to 3 weeks for the grapes to dry. To minimise the time and retain the light colour farmers use a Potassium carbonate and olive oil solution which cracks the invisible membrane on the grape and speeds the drying time. Grapes dried in this manner are called Sultanas.