Dark copper to very black, imperial stouts typically have a high alcohol content. The extremely rich malty flavor and aroma are balanced with assertive hopping and fruity-ester characteristics. Bitterness can be moderate and balanced with the malt character or very high in the darker versions. Roasted malt astringency and bitterness can be moderately perceived but should not overwhelm the overall character. Hop aroma can be subtle to overwhelmingly hop-floral, -citrus or -herbal. Diacetyl (butterscotch) levels should be very low.
This style may be subcategorized into black and quite robust “American” versions and dark copper colored and caramel accented “European” versions.