Is USDT always 1 dollar?

Could you please clarify, is the value of USDT always guaranteed to be equal to 1 US dollar? I understand that USDT, as a stablecoin, is designed to maintain a stable value relative to the US dollar, but are there any circumstances or factors that could potentially cause its value to deviate from this 1:1 peg? Additionally, how does the Tether organization ensure that the value of USDT remains stable and backed by a corresponding amount of US dollars in their reserves?