What is ristretto?

A ristretto is a smaller, more concentrated serving of espresso. It is espresso for the advanced drinker – an essence of coffee that leaves a strong, lingering aftertaste. Rich in sweetness and flavor, a ristretto shot has more body than a regular shot of espresso. In practice, baristas pull only the first portion of a full length espresso extraction, which is why the ristretto is commonly referred to as a “short shot.”

Originally this meant pulling a hand press faster than usually using the same amount of water as a regular short of espresso. Since the water came in contact with the grinds for a much shorter time the caffeine is extracted in reduce ratio to the flavorful coffee oils. The resultant shot could be described as bolder, fuller, with more body and less bitterness.

Typically ristretto is half the volume of normale, and lungo is double to triple the normale volume. For a double shot, (14 grams of dry coffee), a normale uses about 60 ml of water. A double ristretto, a common form associated with artisanal espresso, uses half the amount of water, about 30 ml. Ristretto contains less caffeine than a lungo.
What is ristretto?