Grapes are the fruit of grapevines. Vitis vinifera and Vitis labrusca are two common grapevine species. Vitis labrusca is commonly known as Concord grape.
The whole fruit, skin, leaves, and seed of grape are used as medicine. Grape contains flavonoids, which can have antioxidant effects. They might help prevent heart disease and have other beneficial effects. Red grape varieties provide more antioxidants than white or blush grape varieties.
People use grape for poor circulation that can cause the legs to swell. It is also used for eye stress, heart disease, high cholesterol, high blood pressure, obesity, and many other conditions. But there is no good scientific evidence to support most of these uses.
Don't confuse grape with grapefruit. These are not the same.