Passage: Gringotts Wizarding Bank is the only known bank of the wizarding world and it is operated primarily by goblins. A snowy white building, near the intersection of Knockturn Alley and Diagon Alley, Gringotts towers over all neighbouring shops. Customers pass through a set of bronze doors and then silver ones before entering the lobby. The main floor is paved with marble and has a long counter stretching along its length, behind which goblin clerks work at tasks such as counting coins and updating account ledgers. Within, wizards and witches keep their money and other valuables in vaults that are protected by very complex and very strong security measures. The vaults extend for miles under London and are accessible through rough stone passageways navigated by magic carts that travel speedily along their tracks.[PS Ch.5] Gringotts also offers Muggle-Wizarding currency exchange.[CS Ch.4]When Harry first visits Gringotts, he is told by Hagrid that one would have to be mad to try to rob Gringotts.[PS Ch.5] Goblins are extremely possessive and will protect their money and valuables at any cost, making them ideal guardians for the valuables of the wizarding world. In addition, according to Hagrid, apart from Hogwarts, Gringotts is considered "the safest place in the world for anything you want to keep safe".There are a number of methods of opening the vaults. Most vaults, such as Harry's, use small golden keys. Higher-security vaults may have various enchantments or other measures upon the doors. For example, the door to Vault 713, which briefly contained the Philosopher's Stone, must be stroked by a certified Gringotts goblin, whereupon it melts away to allow access to the contents. If anyone other than a certified Gringotts goblin touches the door, that person will be sucked into the vault, which is only checked for trapped thieves about once every 10 years. Dragons guard the maximum-security vaults found in the lowest reaches of the bank, and a subterranean waterfall called the "Thief's Downfall" acts to overturn...

Question: Gringotts bank is used by what type of supernatural creatures?
wizards and witches