USD Tether is a Bitfinex issued ERC-20 token which is claimed to be backed by dollar at 1:1 ratio. There are controversial opinions about this and some say it's a scam.
Do you trust USDT or believe it might be a scam?
I don't trust it completely because it's not an altcoin. It only adds technology to bitcoin. Their projects are still obscure. I often use it as an intermediary coin to trade other coins. Its price also varies a lot and is always changing. But I used to use it for profit. Buy and sell.