1. Tectonic Plate Collisions: This is the most common way mountains are formed. When two tectonic plates collide, the denser plate is forced beneath the lighter plate in a process called subduction. This creates immense pressure and heat, leading to the formation of volcanoes and the uplifting of the land to form mountains. The Himalayas, Andes, and Alps are all examples of mountains formed this way.

2. Fault Block Mountains: These mountains are formed when blocks of Earth's crust are uplifted along fault lines. The Sierra Nevada mountains in California are an example of fault block mountains.

3. Volcanic Mountains: These mountains are formed when molten rock, or magma, erupts from the Earth's surface. As the lava cools and hardens, it builds up over time to form mountains. Mount Fuji in Japan and Mount Kilimanjaro in Africa are examples of volcanic mountains.