#3 Tether (USDT) in minutes: what it is, why it was created, and what it's for
USDT is the most widely used "crypto dollar": its goal is to be worth ≈ 1 USD so you can move around in crypto without typical volatility. 
What is it?
USDT is a stablecoin (stable currency) issued by Tether, designed to maintain a 1:1 parity with the US dollar. 
Why was it created?
To have a "digital dollar" within the crypto ecosystem: facilitate trading, payments, and transfers without constantly entering and exiting banks, and reduce volatility when holding BTC/ETH without wanting price exposure. 
How does it work?
Tether issues (mints) USDT and claims to maintain reserves backing the tokens; it publishes information and reports/attestations on its transparency page. 
What is it used for today?
✅ Trading: "parking in dollars" without leaving the exchange
✅ Payments/transfers: move value with stable pricing (depending on network and fees)
✅ Remittances: send "dollars" digitally through some brokers
✅ Bridge to DeFi: enter/exit protocols without volatility (depending on platform) 
Quick facts
• Launch: 2014 
• Operates on multiple networks (depends on the USDT you use) 
Risks / limitations (direct)
• Issuer/reserve risk: depends on the management and transparency of the backing
• Regulation and freezes: stablecoins may be subject to compliance actions (freezing addresses) $USDT
• Not for "growth": it's for stability, not appreciation.