The Lock is an item that is used in order to secure chests, so that only the one who made the lock can access it. This is especially helpful if you often get your items stolen (like if you don't have a secure base, or if you don't trust your peers). Note that you can still break a locked chest and any items inside will disappear, just like a normal chest. To remove a lock, a key is required. When a key is used on a lock, both the lock and the key are destroyed, granting free reign over the chest.