Imagine the Earth is like a giant puzzle made up of big, moving pieces called plates. When these plates push against each other or crash together, they can form mountains, just like when you stack blocks and make a hill.
The Big Push
Sometimes, two plates collide, and instead of one going under the other (like a car crash), they push up into the sky, making tall mountains. This is how the Himalayas formed, by Earth’s biggest plate collision.