A stable coin in the simplest sense could be seen as, “… a cryptocurrency that has a price-stable characteristic. Its value is pegged to or tied to another stable asset, like gold or the U.S. dollar. Its glamor comes from its extremely low volatility and independence from any central bank. Having a currency that is completely separate and apart from fiat is game changing and what is believed to be the future of digital money. Imagine having an infinite usage of digital money anytime, anywhere.” (Source: https://www.forbes.com/sites/andrewrossow/2018/09/07/stability-in-volatile-markets-what-you-need-to-know-about-stable-coins/?sh=365c9c2a226c)
There is still debate and questions regarding this, though the use of this and the technology used is continuing to evolve.