Order book DEXes (Decentralized Exchanges) need the buyers and the sellers to agree at a fair market price for the tokens. But the buyers want to spend as low as possible to buy the tokens. And the sellers want to get as much as possible for their tokens. This creates a stalemate where neither the sellers nor the buyers budge. And so the trade can't go on. So the only way to facilitate trade is by bringing in someone willing to buy and sell specific tokens at any price. These people are aptly called market makers. Automated market makers use smart contracts and liquidity pools to get the job done. This makes the process decentralized and permissionless. Anyone can set up liquidity pools for the tokens of their choice. And they don't have to pay any listing fees or meet any admission criteria for that. Since providing liquidity is something anyone can do with AMMs, fans, and holders of new tokens can create a liquid market for it. And that goes a long way in helping new projects grow.