Mustard seeds are the small round seeds of various varieties of mustard plants. The seed is usually about 1 or 2 mm in diameter and is an important spice in many regional foods. Mustard seed is one of the most popular spices traded in the world today. As it grows well in temperate climates, the areas that produce the greatest amount of mustard seeds currently include South Africa, Hungary, Great Britain, Canada and the United States. Mustard, one of the most ancient spices has 3 varieties namely black, brown and yellow. The black mustard plant normally grows to a height of 10 feet. Brown mustard plant produces tiny yellow colored flowers, which almost cover the plant. White mustard is the mildest among all the varieties of mustard. The seeds have fresh aroma and slightly biting flavour. Mustard seeds have many medicinal properties and it is also used in salad dressings, egg dishes, cheese dishes, pickles and vegetables.