Horseradish is a root vegetable from the Brassicaceae family (which also includes mustard, wasabi, broccoli, and cabbage) It is used as a spice and prepared as a condiment.
The plant is likely to be native to southeastern Europe and western Asia but is popular worldwide.
The intact horseradish root has hardly any aroma but when sliced or grated, certain enzymes from the broken plant cells break down sinigrin (a glucosinolate) to produce allyl isothiocyanate (mustard oil), which irritates the mucous membranes of the sinuses and eyes.
Once grated, Horseradish can either be used immediately or preserved in vinegar for best flavor. Horseradish sauce is the most common way to use horseradish.