What is the bitcoin lightning network?

Lightning network is a distributed network that enables instant payment across the participant network through the smart contract function, while taking advantage of the blockchain feature to eliminate the risk of hosting funds to third parties. Mainly used for instant, high-volume micropayments. In essence, it is to set up another channel outside the bitcoin main chain, where users' digital currency can make quick payments, because the lightning network is a decentralized architecture, which is fundamentally different from traditional exchanges.