"What is the difference between collateralized stable coins USDT, USDC and DAI?"
#JeremyAnswers
USDT is issued by Tether, a HK based company. It has the highest market cap and the most trading pairs out of the 3.
In the past, USDT was involved in some controversy regarding the transparency of it's reserves. This no longer appears to be an issue:
tether.to/en/transparency/#reports
DAI was created by MakerDAO. It is the only coin out of the 3 which is fully decentralized and is therefore the most resistant to tampering.
To mint DAI you must deposit collateral, many forms are accepted including ETH.
As the value of your collateral can fluctuate, you must deposit it at a ratio >= 150%.
If the value of your collateral falls below 150%, it is liquidated to pay off your loan.
It is common to deposit at a ratio > 300% to protect your assets.