What is decentralized USD?

Could you please explain what decentralized USD actually means? I'm quite intrigued by the concept but am not entirely sure how it differs from traditional fiat currencies. Is it a type of cryptocurrency? And if so, how does it work? I'm also curious about its potential benefits and drawbacks compared to centralized financial systems. Could you elaborate on its use cases and the reasons why someone might want to use decentralized USD? Additionally, I'm wondering about its legality and how it's regulated in different jurisdictions. Thank you for your clarification.