What can you swap on Uniswap?

Can you tell me more about the range of assets that can be swapped on Uniswap? I'm curious about the types of cryptocurrencies and tokens that are available for trading on this decentralized exchange platform. Is it limited to just Ethereum-based assets, or can I also swap for other blockchain-based assets? Additionally, are there any specific restrictions or requirements for the assets that can be listed on Uniswap? I'd like to have a clear understanding of what kind of swaps I can potentially make on this platform.