LP stands for "liquidity provider" in DeFi, and refers to individuals or entities that provide liquidity to decentralized exchanges (DEXs) by depositing funds into a liquidity pool. In return, LPs receive a portion of the trading fees generated by the DEX in proportion to their contribution to the pool.
Liquidity pools are essentially smart contracts that hold two or more tokens in equal value. When a user wants to trade one token for another on a DEX, the trade is executed by swapping tokens with the liquidity pool. The price of the token being bought/sold is determined by a mathematical formula based on the amount of each token in the pool.
For example, let's say an LP deposits equal amounts of ETH and DAI into a liquidity pool. If someone wants to trade ETH for DAI, the trade is executed by swapping ETH with the liquidity pool, which sends back an amount of DAI based on the current exchange rate. The price of DAI in ETH terms is calculated by dividing the total amount of DAI in the pool by the total amount of ETH in the pool.
LPs earn a portion of the trading fees generated by the DEX, which are usually set at a percentage of the trade amount. For example, if the fee percentage is 0.3%, an LP would earn 0.15% for every trade in which they provided liquidity to the pool. This creates an incentive for LPs to provide liquidity to DEXs, and helps ensure that there is sufficient liquidity available for traders to execute their trades.