How much is a dollar in chain?

Excuse me, as a keen observer of the cryptocurrency market, I'm curious to know how the value of a traditional dollar translates into the chain economy. Could you elaborate on the current exchange rate between fiat currency and, say, Bitcoin or Ethereum? I understand that cryptocurrencies are highly volatile, but I'm seeking a general understanding of how the dollar stacks up in the blockchain world. Additionally, are there any specific factors or metrics that influence this exchange rate, and how does it typically fluctuate? Thank you for your insight.