Add To Pile

Add To Pile or Piling is an action performed by pressing the appropriate button when available.

This is the action to place/drop/stack multiple items into a pile. This physical pile of items is known as a stockpile.

Grabbing is the action of taking an item off of a stockpile.

Mechanics
The items to add to the pile have to be the same item. You can't stockpile different items into the same pile.

You have to be close enough to the pile of items and oriented in the correct direction to be able to add an item to a stockpile.

All items which can be interacted with can be added to a stockpile. Even rare items such as Meteorites and  Precious Stones can be stockpiled.

The stockpile cannot contain infinite items and is limited 25 items per stockpile.

Stockpiles stop changing visually in the game after adding 11 items to the stockpile, however you can still add up to 25 items to the stockpile.

Clan members can  both  add to and take from the stockpiles.

Some stockpiles of items can be picked up and moved with the carry action. This allows moving the stockpile as a single item instead of having to pick up and move each item individually.

Add to pile is the first step in the construction process.