Lighting Labs Releases Lightning mainnet Server lnd 0.4-beta. While focused on developers this is the first release that runs on mainnet that uses real bitcoin. https://blog.lightning.engineering/announcement/2018/03/15/lnd-beta.html
The original Lightning Network 2015 Whitepaper. "Creating a network of micropayment channels enables bitcoin scalability, micropayments down to the satoshi [1/100m Bitcoin], and near-instant transactions."