Packing peanuts are small, lightweight foam pieces used to protect fragile items during shipping and storage. They fill empty spaces in boxes, preventing movement and reducing the risk of damage to the contents. These materials are typically made from either expanded polystyrene (EPS) or biodegradable alternatives like cornstarch. While traditional packing peanuts are not recyclable, some companies offer eco-friendly options that can dissolve in water, making them a more sustainable choice for packaging.