Gueuze (or Geuze) is a type of lambic, a Belgian beer. It is made by blending young (1-year-old) and old (2- to 3-year-old) lambics, which is then bottled for a second fermentation. Because the young lambics are not fully fermented, the blended beer contains fermentable sugars, which allow a second fermentation to occur. Lambic that undergoes a second fermentation in the presence of sour cherries before bottling results in kriek lambic, a beer closely related to gueuze.