Imperial IPAs, or often double IPAs (dIPAs), are exactly what their name implies, extra strength imperial pale ales. Imperial IPAs are uniquely American creations, originating in the late 1990's and exploding into the heart of the hop hungry American craft brewing scene in the early 2000's. Like IPAs, they range in color from gold/amber to reddish copper. They feature aromas and flavors comparable to IPAs, but with more hop intensity, a richer malt base, a heavier mouthfeel, and a higher but not overly noticeable alcohol presence. Although their typical alcohol content of 7.5-10% overlaps that of barleywines, dIPAs are usually hoppier than barleywines, which tend to be hop-malt balanced or more malty than hoppy.
