We've all opened a bar tab before, right?

You put your card down, order drinks throughout the night, the bartender keeps track of your total spend - then at the end of the evening, you settle up.

If you've ever wondered how a 'layer 2 scaling solution' works on blockchains like Ethereum, it's pretty much that .

Ethereum is the credit card, and the layer 2 is the bartender tracking your spending.

Instead of swiping your credit card, signing the check, and paying a transaction fee every time you want a drink - you only need to make two of these costly and time-intensive transactions:

1. When starting the tab (sending your Ethereum to a layer 2).

2. When closing the tab (collecting what remaining Ethereum you have left over).

All of the small transactions you make in between are super fast and (almost) free of fees, because it's just being added/subtracted from your tab - the settlement doesn't have to take place every time.

Ethereum's transaction fees are way too high to support small transactions at high volume (who wants to pay a $20 transaction fee on a $5 purchase?) - so there's a huge rush to create the winning layer 2 scaling solution.

This linked article focuses on what these competing layer 2's need to achieve in order to become dominant players in the space.

According to the CEO of Arbitrum (a layer 2 solution), there are three targets to hit:

1. A bunch of people need to be able to use them at once (scalable)

2. The system needs to be safe for everyone to use (secure)

3. It needs to be accepted everywhere and play nice with others (interoperable)

We'd add to that list:

4. 'Dad needs to be able to use it, without calling for help' (easy to use).

It's a hard cocktail to mix, but one that is vital to the widespread adoption of Ethereum.