The Andes are the mountain range that runs along the western coast of South America. Stretching roughly north–south beside the Pacific, the range forms the continent’s mountainous western backbone.
The Andes extend through seven countries: Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile, and Argentina. They are about 8,900 kilometers long, making them the longest continental mountain range in the world. Their highest summit is Aconcagua in Argentina, which rises to approximately 6,961 meters and is the highest mountain outside Asia.
The range exists because the oceanic Nazca Plate is being forced beneath the South American Plate, a process called subduction. That ongoing tectonic activity explains why the Andes contain active volcanoes and experience frequent earthquakes. The range also includes high plateaus such as Bolivia’s Altiplano.
The Andes are sometimes confused with the Rockies because both belong to the American Cordillera, the broader chain of mountain systems along the western side of the Americas. The Rockies are in North America; the Andes are the South American section.