The potato is a starchy, tuberous crop from the perennial nightshade Solanum tuberosum, native to the Americas. In many contexts, potato refers to the edible tuber, but it can also refer to the plant itself. Common or slang terms include tater, tattie, and spud. Wild potato species can be found throughout the Americas, from the United States to southern Chile. The potato was originally believed to have been domesticated by indigenous peoples of the Americas independently in multiple locations, but later genetic testing of the wide variety of cultivars and wild species traced a single origin for potatoes. In the area of present-day southern Peru and extreme northwestern Bolivia, from a species in the Solanum brevicaule complex, potatoes were domesticated approximately 7,000–10,000 years ago. In the Andes region of South America, where the species is indigenous, some close relatives of the potato are cultivated. Potatoes were introduced to Europe from the Americas in the second half of the 16th century by the Spanish. Today they are a staple food in many parts of the world and an integral part of much of the world's food supply. As of 2014, potatoes were the world's fourth-largest food crop after maize (corn), wheat, and rice.