What network is Uniswap on?

Excuse me, could you please clarify which network Uniswap operates on? As a decentralized exchange, it's important to understand the underlying blockchain infrastructure that supports its transactions. Is Uniswap built on Ethereum, or is it hosted on a different blockchain altogether? This information is crucial for users to consider when trading tokens and understanding the associated fees, speed, and security implications. Thank you in advance for your clarification.