Tether always stays between .99 and 1.01. How, I dont know. With it never really changing in price, why not convert your cryptos to tether to avoid losses when the market is crashing?
The concept of Tether is to be the digital dollar but the main problem with them is that they are not transparent, if you are following the market you should know that they have produced many coins in a short period of time without any transparency or any audit, so i would stay away from them simply because of their shady behavior.