Tether (USDT) is a stablecoin cryptocurrency that is hosted on the Ethereum and Bitcoin Blockchains, among others. Its tokens are issued by the Hong Kong company Tether Limited, which in turn is controlled by the owners of Bitfinex. Tether is called a stablecoin because it was originally designed to always be worth US$1.00, maintaining $1.00 in reserves for each tether issued.