I've had a few posts about bitcoin and other cryptos, as well as PoW vs PoS, with PoS allowing one to earn interest from the staking. Now, we come to the concepts around Stable Coins.
The basics are that these coins are backed up by another asset. Some may be backed by another crypto, like Maker with Etherum. Others, like USDT, TUSD, or CNY are backed by dollars, Chinese Yuan, or others.
The idea is to have the same flexibility as cryptos, but without the volatility. Some are very centralized, so may not have the spirit of cryptos, while some have various degrees of decentralization. The advantage is that, as the working theory goes, you have 1 Stable, you can exchange it readily for 1 Fiat.
As with other cryptos, beware that you may not be able to purchase them in all jurisdictions.