Raisins, produced and eaten as snacks and used in cooking throughout the world in dishes both savory and sweet, are simply dried grapes. Most are dried in the sun or by mechanical means. "Golden raisins" are made from the same grape as dark raisins (Thompson seedless, mostly), but are treated with sulfur dioxide and flame-dried to give them their characteristic color. A particular variety of seedless grape, the Black Corinth, is also sun dried to produce Zante currants, mini raisins that are much darker in color and have a tart, tangy flavor.
Other dried fruits, such as sweetened cranberries, can often take the place of raisins.
Some recipes may call for raisins to be soaked in warm water to plump them.
Store raisins tightly wrapped to prevent them from drying out; they'll keep for months at room temperature.