Do you need ETH to use Uniswap?

Hello there, I have a quick question regarding Uniswap and its use. I've been hearing a lot about this decentralized exchange lately and I'm curious if I need to have ETH in my wallet in order to use it? I'm still relatively new to the world of cryptocurrency and I'm trying to get a better understanding of the process. If you could clarify this for me, I would greatly appreciate it. Thank you!