A Lightning Service Provider, or LSP, is an entity that facilitates various liquidity and network services on the Lightning Network for users and businesses.

LSPs act as intermediaries, similar to how Internet Service Providers (ISPs) offer internet access. They provide various services, such as opening channels, routing transactions, and better connectivity, as well as more advanced features like channel rebalancing and zero-conf channel openings.

Their primary role is to enhance user experience by handling more complex tasks like swapping on-chain and off-chain funds and adjusting a user's position within the network. LSPs often charge fees to cover mining expenses, capital costs, and for their specialized services.

When comparing an LSP to another Lightning service, such as a LaaS, LSPs focus specifically on liquidity and network services, whereas LaaS providers may offer a broader range of infrastructure solutions.