Mountains are large landforms that rise prominently above their surroundings, often characterized by steep slopes and rugged terrain. They are formed through tectonic forces, volcanic activity, or erosion. Mountains can be found in ranges, such as the Himalayas or the Rocky Mountains, and they often have diverse ecosystems due to varying altitudes and climates. Plains, on the other hand, are flat or gently rolling areas of land that cover large regions. They are typically formed by sediment deposition from rivers or glacial activity. Plains, like the Great Plains in North America, are often used for agriculture due to their fertile soil and easy accessibility.