What is Bitcoin Lightning ?

Since the Bitcoin’s blockchain can handle around seven transactions per second (TPS), the network’s scalability eventually became an issue, and a second-layer solution was suggested called the Lightning Network (LN). 

LN solution enabled split-second Bitcoin transactions in high volumes between users, without the need for network confirmations. By opening Lightning channels “off-chain”, users can transact between each other for infinity, and settle only the final amount. LN transactions themselves cost close to nothing and allows sending smallest fractions of Bitcoin.

Here’s where you can find more information about the Lightning Network.