Here's why:

* Folding: Folding occurs when rocks are subjected to compressional forces. This squeezing causes the rock layers to bend and buckle, creating folds.

* Mountain Formation: The upward, folded sections of the rock layers often form the peaks and ridges of mountains.

* Other Features: While mountains are the most prominent feature formed by folding, other landforms can also result, such as valleys, plateaus, and hills.

Examples:

* The Appalachian Mountains in North America

* The Himalayas in Asia

* The Alps in Europe

It's important to note that while folding plays a significant role in mountain formation, other processes like faulting (breaking and shifting of rock layers) and volcanic activity also contribute to the creation of these impressive geological features.