The Spine of South America
The Andes mountains are located in South America. They run like a great spine down the entire western edge of the continent, stretching from the north all the way to the southern tip. The Andes are the longest mountain range on land anywhere in the world, and they pass through seven different South American countries.
How the Andes Were Formed
The Andes exist because of the slow, powerful movement of the Earth's crust. Off the western coast of South America, a heavy oceanic tectonic plate is being forced beneath the continental plate that carries the continent. As the ocean plate dives down, the edge of the continent is squeezed and crumpled upward over millions of years. This crumpling is what pushed up the towering peaks of the Andes, and the process is still going on today.
A Range of Earthquakes and Volcanoes
Because the Andes sit directly on the boundary between two tectonic plates, the region is geologically very active. Earthquakes are common all along the range, and the Andes are dotted with many volcanoes, some of them among the highest in the world. This places the Andes within the wider zone of earthquake and volcanic activity that rings the Pacific Ocean.
A Land of Extremes
The Andes are a land of dramatic contrasts. They contain high, cold plateaus, deep valleys, and snow-capped peaks, including Aconcagua, the highest mountain anywhere outside of Asia. The range was also home to great ancient civilizations, most famously the Inca, whose mountain city of Machu Picchu still draws visitors from around the world. Today millions of people live in the Andes, often at altitudes that would leave most visitors short of breath.
Source
This article was written using information from Wikipedia.