What is Polkadex?

So, I'm curious, what exactly is Polkadex? I understand it's somehow related to blockchain and cryptocurrency, but can you give me a more detailed explanation of what it is, how it works, and what sets it apart from other similar platforms? Is it a decentralized exchange? Does it offer any unique features or advantages? And finally, what are some potential use cases for Polkadex? I'm eager to learn more.