Sauerkraut is finely chopped cabbage which has been stored with salt and fermented, which adds beneficial bacteria nowadays fashionably known as probiotics. The fermentation conserves vitamins using a pickling method that was traditional before frozen food and rapid food transport became available. Preserved cabbage, such as also Korean kimchi, was in many places a staple winter food in the absence of fresh produce. Sauerkraut keeps without refrigeration, and although it may be served heated, heating actually destroys the beneficial bacteria.
English has no homegrown term for this food, which is widely eaten in Europe and thought to have arrived there from the far east, possibly with Genghis Khan. In German sauer means sour and Kraut means herb, or leaves and stem of a plant, but in compound words -kraut forms names for types of cabbage, with Rotkraut meaning red cabbage for example.
Sauerkraut also played a key role in the expansion of European empires and sea trade from the late eighteenth century because it helped end the crew deaths caused by scurvy, a disease that would previously kill half the crew on a long sea voyage due to them lacking vitamin C in their limited diet.
From 1918 Kraut is known as an anglophone derogatory name for Germans, with a rather more neutral usage emerging in the 1970s in the UK to describe experimental German rock music as Krautrock.