The Lightning Network is a layer 2 payment protocol that is built on top of the Bitcoin blockchain. It is a way of enabling fast and cheap transactions on the Bitcoin network, by using a network of payment channels that are off-chain, or outside of the main blockchain. The Lightning Network allows users to open a payment channel with one or more other users, and to make unlimited transactions between them without having to broadcast each transaction to the blockchain. This allows for faster and cheaper transactions, as the fees and the confirmation times are much lower than on the main blockchain. The Lightning Network also has the potential to enable new types of applications and use cases for Bitcoin, such as instant micropayments and cross-chain atomic swaps.