One of the world's most popular spices, black peppercorns are actually unripe green fruits (berries) that have been sun-dried after fermenting. Black, white and green peppers all come from the woody tropical plant Piper nigrum.
Pepper berries are at first green; they turn red as they ripen. The stage at which they're harvested (and whether or not they are husked) determines the color of the resulting spice. Black pepper is harvested while the berries are still green--before ripening. Sun drying turns them dark brown and wrinkly. White pepper results when the berries are picked fully ripe and then husked and dried. Green peppercorns are picked before ripening and preserved before drying. Pepper's rich history can be traced through the records of ancient Rome, the monastic records of the Middle Ages, and the logs of early traders and explorers. In 1180, A Guild of Pepperers-- the most important guild of the time-- was in existence in London. Often equated with money, pepper has been used for taxes, rent, dowries and ransom. When Alaric the Goth besieged Rome, gold, silver, and pepper were demanded as ransom. (The gold and silver were easy enough to come by, but the pepper gave them some trouble.) The quest of pepper largely defines the history of the spice trade.