Tether (USDT) is a digital currency pegged to the value of the US dollar. Initially, it used the Omni layer on the Bitcoin network for its transaction protocol, but now Tether is also available on Ethereum as an ERC20 token. Currently, it is the third-largest cryptocurrency by market capitalization, after Bitcoin and Ethereum.
Because Tether's value is directly linked to the US dollar, with a 1:1 exchange rate, it exhibits more price stability compared to other cryptocurrencies that are more volatile. This makes Tether a popular choice among cryptocurrency investors to mitigate the effects of market fluctuations, helping to reduce the transaction costs associated with converting between different currencies.
Reference: CoinMarketCap