Enter, the Lightning Network (LN) , a Layer 2 bitcoin scaling solution.

'Layer 2' means it is built on top of bitcoin.

'Scaling Solution' means it allows the network to:

Vastly increase the speed of processing.

Vastly increase the number of transactions it can process per second.

Make micropayments possible.

The Lightning Network can be (sort of) thought of like a tab you might keep with some friends at the bar.

You keep track between all of you who owes what (like a Lightning Network channel), and at the end of the night your group settles with the barman ('the mainchain').

Lightning channels, however, can stay open for days, weeks, months or years before being 'settled' on the mainchain.