TL;DR
A liquidity pool is a pair of tokens locked in a smart contract that enables decentralized trading. Liquidity providers deposit both tokens and earn a share of trading fees in return.
Instead of matching buyers with sellers through an order book, Solana DEXs like Raydium and Orca use liquidity pools — smart contracts holding reserves of two tokens (e.g., SOL/USDC). When someone trades, they swap against the pool rather than another person. The pool uses a pricing formula (constant product, concentrated, or hybrid) to determine the exchange rate. After each trade, a small fee is added to the pool, rewarding the liquidity providers who deposited the tokens.
To become a liquidity provider (LP), you deposit equal value of both tokens into a pool. In return you receive LP tokens representing your share. Your earnings come from the swap fees generated by the pool — typically 0.01% to 1% per trade depending on the pool tier. On Solana, depositing and withdrawing is fast and cheap compared to Ethereum. Many pools also offer additional farming rewards in the form of governance or protocol tokens.
Raydium offers both constant-product pools (AMM v4 and the newer CPMM program) and concentrated liquidity (CLMM) pools. Orca uses concentrated liquidity through Whirlpools. Meteora uses dynamic liquidity with its DLMM model. Concentrated liquidity lets LPs focus their capital in a specific price range for higher fee efficiency, but requires more active management. Standard pools are simpler — deposit and forget.
The main risk is impermanent loss — when the price ratio of the two tokens changes, you end up with less total value than if you had just held the tokens. This loss becomes permanent if you withdraw at an unfavorable ratio. Other risks include smart contract bugs, rug pulls on the token you’re pairing with, and low trading volume that doesn’t generate enough fees to offset the impermanent loss. Always check pool analytics and volume before committing capital.