Uniswap is a decentralized exchange (DEX) protocol built on the Ethereum blockchain. It allows users to trade cryptocurrencies and other digital assets without the need for intermediaries such as centralized exchanges or brokers.

Uniswap uses an automated market-making (AMM) mechanism to enable trading on its platform. This means that instead of relying on a traditional order book, Uniswap uses smart contracts to create liquidity pools for different pairs of tokens. These pools are automatically maintained by algorithms that adjust the prices of the tokens based on the supply and demand.

Users can trade any ERC-20, BEP20, Polygon token on Uniswap, and they can also provide liquidity to the pools by depositing tokens and earning a share of the trading fees. Uniswap's native token is UNI, which was introduced in September 2020 and is used for governance and liquidity incentives.

To exchange tokens on Uniswap, you can follow these steps:

1. Connect your wallet: You need to connect your wallet that holds the tokens you want to exchange. Uniswap supports various wallets such as MetaMask, WalletConnect, Coinbase Wallet, etc.

2. Select the tokens: Choose the tokens you want to exchange. Uniswap supports many ERC-20 tokens, and you can search for the token by its name or symbol.

3. Enter the amount: Enter the amount of tokens you want to exchange. You can enter either the amount of tokens or the amount of Ethereum you want to spend.

4. Confirm the transaction: Review the details of the transaction and confirm it. You will need to pay a small fee for the transaction, known as the gas fee, in Ethereum.

5. Wait for the transaction to complete: After confirming the transaction, you need to wait for it to be processed and completed on the Ethereum blockchain. You can track the progress of your transaction on a block explorer like Etherscan.

6. Receive your tokens: Once the transaction is completed, you will receive the tokens you exchanged in your wallet.

Note that the price of tokens on Uniswap is determined by the market demand and supply, and it can change rapidly. Therefore, the actual price you receive may differ from the estimated price at the time of the transaction.