Stone helmet is the second tier of helmets which can be equipped. While wearing it, a player takes less damage from mobs, spikes and other players.
Most players tend to get the backpack before getting the stone helmet, simply to avoid stone helmet taking space in the inventory.
Stone helmet is the upgrade of the wooden helmet. It can be further upgraded into the golden helmet.
Stone Helmet is crafted using 75 wood, 75 stone, and a wooden helmet near a workbench. It can be upgraded to a golden helmet.