US Dollar Tether. Tether is 1 to 1 with USD and since it is an Alt coin you do not have to pay capital gains yet since technically you did not trade an asset into US currency. I would consult your tax attorney of course but that is how I have come to understand it.

Usd is our fiat currency known as the dollar. Usdt is the 1=1 currency known as Tether. It is a pegged currency that keeps the value of itself equal to the value of the American dollar.