A liquidity pool is a crowdsourced pool of cryptocurrencies or tokens locked in a smart contract that is used to facilitate trades between the assets on a decentralized exchange (DEX). Instead of traditional markets of buyers and sellers, many decentralized finance (DeFi) platforms use automated market makers (AMMs), which allow digital assets to be traded in an automatic and permissionless manner through the use of liquidity pools.
AMMs fix the problem of limited liquidity by creating liquidity pools and offering liquidity providers the incentive to supply these pools with assets, all without the need for third-party middlemen. The more assets in a pool and the more liquidity the pool has, the easier trading becomes on decentralized exchanges.
In the early phases of DeFi, DEXs suffered from crypto market liquidity problems when attempting to model the traditional market makers. Liquidity pools helped address this problem by having users be incentivized to provide liquidity instead of having a seller and buyer match in an order book. This provided a powerful, decentralized solution to liquidity in DeFi, and was instrumental in unlocking the growth of the DeFi sector. Liquidity pools may have been born from necessity, but their innovation brings a fresh new way to provide decentralized liquidity algorithmically through incentivized, user funded pools of asset pairs.