Tether (USDT) is a stablecoin pegged to the US dollar and was the first stablecoin to exist. USDT was initially launched as Realcoin in 2014 by entrepreneur Reeve Collins, Bitcoin investor Brock Pierce, and developer Craig Sellers. It has since become the largest stablecoin by market cap. Tether tokens are issued by Tether Limited, a company controlled by the owners of crypto-exchange Bitfinex.
While Tether was originally only available on the Bitcoin network through Omni Layer, the stablecoin is now available on several blockchains. You can now trade USDT on Ethereum, TRON, Solana, Algorand, the OMG network, and EOS.
Tether is backed by a mixture of fiat and commercial paper reserves. With approval from Tether Limited, you can switch between USD and Tether, a mechanism that helps keep the stablecoin's peg. USDT has been the subject of some controversy, as investors and regulators often claim that the stablecoin isn't fully collateralized. Tether has had to defend the point many times in court and still is yet to reveal a full audit of their funds.