In a nutshell:
USDT was back at par with the USD today.
What is USDT?
USDT is USD Tether. It's a "coin" on some exchanges, a low/no volatility place where you could park your money instead of riding the ups and downs of BTC or some other crypto coin. Because of an alleged 1:1 reserve of fiat currency, tether was supposed to always be $1 or so close as not to matter.
What happened?
As you may or may not know, you could count on USDT to be close enough to $1 all the time, until about a month ago. That's when problems at Bitfinex and who knows what else, caused the tether to break. USDT was at or near as low as $0.91/USDT at one point. That means your $1 Tether was worth less than $1.
Who cares?
Honestly, almost no one cares. As long as you were just moving in and out of Tether to and from other cryptos, it didn't much matter. You still benefited from the low volatility of Tether dollars. But if you attempted to move your USDT to USD, you could get less real dollars for your Tether dollars.
The only other reason it matters is that some exchanges use a USDT bitcoin price. And these were, by definition, inflated relative to the USD price. For example, at $0.91 USDT, your $2000 bitcoin would have shown more like a $2197 Tether price. Poloniex for example. So before quoting some gigantic Bitcoin price, make sure you are quoting a real USD price and not the potentially "wrong" USDT price.
Will it hold?
I have no idea. Can't seem to find any news on the Google to explain why it is back up. I wouldn't trust it if I was planning to go back and forth between USD and USDT. I mean if the unbreakable tether could break once, it could break again. But I think it is still fine to park in Tether on the exchanges. Temporarily. If I'm wrong, please let me know!