A mountain is a large land form that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill. Mountains are formed through tectonic forces or volcanism. These forces can locally raise the surface of the earth by over 10,000 feet (3,000 m). Mountains erode slowly through the action of rivers, weather conditions, and glaciers. A few mountains are isolated summits, but most occur in huge mountain ranges.
The highest mountain on Earth is Mount Everest in the Himalayas of Asia, whose summit is 8,848 m (29,029 ft) above sea level. The highest known mountain in the Solar System is Olympus Mons on the planet Mars at 21,171 m (69,459 ft). From Wikipedia.