Mustard seeds are the seeds of mustard vegetables, with a diameter of between 1 and 2 millimeters and a color ranging from light yellow to black. They can be crushed and mixed with water, vinegar, etc. to make mustard. Mustard seeds are an important spice in many parts of the world, and Indians use them to mix with other spices to pickle vegetables. Its origins are also worldwide, with black and brown mustard seeds yielding more than yellow.