What can I do with USDT?

I've recently come across this term 'USDT' a lot, but I'm not quite sure what it is or what I can do with it. Could you please explain it to me? Is it a type of currency? And if so, how can I use it? Is it safe to invest in USDT? Are there any specific advantages or disadvantages I should be aware of? Also, how does it differ from other cryptocurrencies? I'm quite interested in learning more about this and potentially incorporating it into my financial portfolio. Thank you for your time and assistance.