A group of mountains is known as a mountain range. A group of ranges that share a common origin and form are a mountain system. A group of systems are a mountain chain. A group of ranges, systems and chains are known as a mountain belt or a cordillera.
Mountains are formed as the Earth’s crust collides, cracks, crumbles, folds and spews. They are found all over the world, including in the oceans. Mountains have steep sides and sharp or rounded edges. The highest point of a mountain is known as the peak or summit. When measured from top to bottom, the world's tallest mountain is Mauna Kea, an inactive volcano in Hawaii. There are many types of mountains, including volcanic mountains, dome mountains, plateau mountains and fault-block mountains.