As you may recall from prior blog posts, there are cryptocoins. The most well know is Bitcoin, and in the space of a year, it went from $970 to $20,000! Then, it dropped to $8k.
While this is good for spectators, traders, and such, it doesn't serve a real good, every day use. How would you like to buy a house, only to find that the money you had to buy a $100k house dropped to $50k! Or, on the other side, if you were selling for $100k, and values raised, and you could have $200k?
Thus entered Tether, what was probably the industry's first stablecoin. Basically, what this means is that a "custodial firm" has reserves of USD (or other fiat), and other assets, so that the crypto is "pegged to the dollar." The biggest advantage is that the fees to send the crypto is so small; much less than wire fees, credit card processing fees, or fees by services such as paypal.