Ghee is the Indian name for clarified butter—the liquid fat produced by melting butter and allowing the water to evaporate and the milk solids to separate out. In India, it's used as a cooking fat and in Hindu rituals. In Ayurvedic (ancient Indian) medicine, it's said to improve digestion, fertility and memory, among other unproven benefits. In the U.S., ghee is often sold as a "gourmet"—and thus pricier—butter.
Because ghee has a higher smoke point than butter, it doesn't burn when used in sautéing and thus may generate fewer harmful free radicals. And it keeps longer.
On the other hand, according to some research, ghee may contain a substantial amount of oxidized cholesterol, making it potentially more harmful to arteries than butter, which has none. And like butter, ghee is high in saturated fat (8 grams per tablespoon), with slightly more calories (110 per tablespoon, versus 100 in butter).