Mustard is a condiment made from the seeds of a mustard plant. The whole, ground, cracked, or bruised mustard seeds are mixed with water, vinegar, lemon juice, wine, or other liquids, salt, and often other flavorings and spices, to create a paste or sauce ranging in color from bright yellow to dark brown.

Mustard seeds, both white and brown, are nearly globular in shape, finely pitted, odorless when whole, and pungent-tasting. White mustard seeds are light yellow in colour and about 2.5 mm (0.1 inch) in diameter. Brown mustard seeds are about the same size but are a darker yellow in colour. The seeds of both types contain similar constituents: about 30 to 40 percent vegetable oil, a slightly smaller proportion of protein, and a strong enzyme called myrosin. When dry or ground into a flour, the seeds are odorless.