UNI is the native token of Uniswap, a leading decentralised exchange (DEX) that runs on the Ethereum blockchain for swapping cryptocurrency tokens and more–any ERC20 token can be listed on Uniswap.
UNI is used for the governance for Uniswap, where owners gain voting shares to influence development decisions of the deck, and can also be used to fund grants, partnerships, liquidity mining pools, and other proposals.