Rice is a grain. A grain is the whole seed of a plant that is grown, harvested and processed for consumption. Rice is the seed harvested from the long, grass-like stalk of the Oryza sativa plant in Asia or the Oryza glaberrima in Africa.
A grain consists of three edible parts, the bran, the germ and the endosperm. When white rice is harvested, the bran and germ are removed, and the remaining grain is polished. Conversely, brown rice is the result of leaving the bran and germ intact. Being that brown rice is a whole grain, it is much healthier than white rice because fewer nutrients are lost due to processing.