Mountain formation occurs primarily through tectonic processes, where the Earth's plates interact. When two plates collide, the pressure can cause the land to buckle and fold, creating mountains. This process is known as orogeny. Another way mountains can form is through volcanic activity. When magma from beneath the Earth's crust erupts, it can build up over time, forming volcanic mountains. Both processes contribute to the diverse landscapes we see today, showcasing the dynamic nature of our planet's surface.