How does dex work?

Sure, here's a possible description in the tone of a questioner: "Hey there, I've been hearing a lot about decentralized exchanges, or DEXs, lately and I'm really curious about how they work. Can you explain to me in simple terms what a DEX is, and how it differs from traditional centralized exchanges? I'm particularly interested in understanding the underlying technology that powers DEXs, and how users can trade cryptocurrencies on them without relying on a central authority.