How much fee does Uniswap take?

Could you please clarify for me, how much fee does Uniswap actually charge for each transaction? I'm trying to compare the costs of different decentralized exchanges and it would be great to have a precise understanding of Uniswap's fee structure. Are there any variables that impact the fee amount, such as the amount of the transaction or the token being swapped? Any information you can provide would be extremely helpful in my decision-making process.