Mustard seeds are small, round seeds derived from various mustard plants, typically from the species *Brassica nigra* (black mustard), *Brassica juncea* (brown mustard), and *Sinapis alba* (white mustard). These seeds are commonly used as a spice in cooking, especially in Indian, Mediterranean, and European cuisines. They have a pungent, slightly bitter taste and can be used whole, ground into mustard powder, or processed into prepared mustard condiments. Mustard seeds are also known for their oil content, which is extracted and used for cooking and in traditional medicine.