The word pile has several meanings:

1. A heap or stack of things placed on top of each other. A pile of dirty laundry might grow on your bedroom floor until laundry day. After raking leaves in autumn, you might jump into a huge pile of them. Libraries have piles of books waiting to be reshelved, and construction sites have piles of lumber or bricks.
2. To place things in a heap. You might pile your plate high with mashed potatoes at Thanksgiving dinner, or pile into a car with your friends (meaning everyone squeezes in together, one after another).
3. The soft, thick surface of a carpet or rug, made of tiny loops or tufts of fabric standing up from the backing. Expensive carpets often have a deep, plush pile that feels soft under your bare feet. When you vacuum, you're cleaning dirt out of the carpet's pile.
4. A large post or beam driven deep into the ground to support a building, bridge, or dock. These massive wooden or concrete piles get hammered down through mud or sand until they reach solid rock or firm soil. Houses built over water rest on piles that keep them from sinking.