The Lightning Network is a new payment protocol that operates on top of bitcoin. Often referred to as the off-chain or 2nd layer scaling approach, LN allows for instantaneous and almost fee-less bitcoin transactions.
Benefits of LN over regular (on-chain) bitcoin transactions:
With LN, you no longer have to pay on-chain miner fees associated with regular bitcoin transactions and will have confirmation that your payment was settled immediately.
Note: Lightning Network is not another digital currency - LN is a payment protocol built on top of the bitcoin blockchain, maintaining the same security/privacy that bitcoin’s 1st layer offers.