The Lightning Network (LN) is live on mainnet: there are already more than 793 nodes and 1683 channels operating on a global level. The most update graphical visualization of LN can be found at this link https://lnmainnet.gaben.win/
LN is a “second layer” payment protocol that operates on top of the Bitcoin Blockchain and allows for instant transactions between participating nodes. It’s the first off-chain tentative solution to provide scalability to the Bitcoin ecosystem. From Wikipedia we read that “it features a peer-to-peer system for making micropayments of digital cryptocurrency through a network of bidirectional payment channels without delegating custody of funds or trust to third parties”. The Lightning Network relies on the latest Bitcoin update that goes under the name of Segregated Witness.
It should be noticed that even if the Lightning Network developers discouraged to use the LN on mainnet as it is still susceptible of bugs/loss of funds etc. this haven’t stopped the community to start exploring this new second transactional layer.
In fact, we saw the first purchase made on a LN transaction. As we write the Bitcoin price is rising from recent lows and is hovering around $11340 as the LN makes Bitcoin in line with its recent competitors.