Mountains are large landforms that rise prominently above their surroundings, typically characterized by steep slopes and a peak or summit. They are formed through tectonic forces, volcanic activity, or erosion. Mountains can be found on every continent and often influence climate and weather patterns in their regions. Valleys, on the other hand, are low areas of land between hills or mountains. They are usually formed by erosion from rivers or glaciers over time. Valleys can be wide or narrow and often contain rivers, lakes, or fertile land, making them important for agriculture and human settlement.