Does arbitrum use ETH or WETH?

Could you please clarify for me if Arbitrum utilizes ETH or WETH? I've been trying to wrap my head around the intricacies of this cryptocurrency ecosystem, and this particular detail seems to be a bit hazy for me. I understand that both ETH and WETH are significant components in the Ethereum network, but I'm not quite sure how they fit into Arbitrum's framework. Would you mind breaking it down for me in a way that's easy to understand? Your explanation would be greatly appreciated as I continue to delve deeper into the world of finance and cryptocurrency.