Many a proud Irishman claims the inventor of whiskey to be Saint Patrick himself, way back from the fifth century.
Irish whiskey, like scotch, is a barley derivative. It's often cut with neutral grain spirits. The malt - half-sprouted barley with oats - is dried in a closed kiln so there's no smoky flavor. With the exception of the Irish coffee, Irish whiskey isn't recommended as a cocktail mixer. It's best enjoyed neat, on the rocks, or with a splash of water.