A stablecoin is a digital asset whose value is pegged to a real-world asset, such as fiat currencies, precious metals (gold, silver, etc), cryptocurrencies or other investments.
The value of a stablecoin is meant to remain relatively stable, even when the prices of other cryptocurrencies fluctuate. This makes stablecoins an attractive option for investors who want to hold onto their assets without having to worry about losing money due to price volatility.
Some of the most popular stablecoins are Tether (USDT) which is one of the oldest stablecoins out there, launched in 2014 and one of the most valuable cryptocurrencies overall by market capitalization.
Then we have the USD coin, launched in 2018, which is pegged to the U.S. dollar. We also have DAI which is a stablecoin on the Ethereum blockchain, created in 2015 and pegged to the U.S. dollar and backed by ether, the token behind Ethereum.