The world’s simplest explanation of Sharding

Understanding blockchain Sharding in 3mins.

Welcome to Intro to Crypto; my 20-part series explaining blockchain and crypto in simple, granny-friendly English.

In The world's simplest explanation of Blockchain, I explained that a blockchain is just a ledger (or 'list') of payments ordered by time. Your bank uses the same sort of thing to keep track of your money; a spreadsheet with 3 columns: money in, money out and final balance. Very simple.

All together now

The main difference with a blockchain is that everyone has copy of the same ledger so nobody can cheat. The problem is 'how do you get them to update their ledgers at the same time?' Because payments are processed batches (or 'blocks') you have to wait until your payment is picked up by the network.

And when there's tens of thousands of payments every second, blocks get full and waiting payments (or 'pending transactions') pile up. Think of it like a 20-storey building with 700 people but only 3 elevators. Inevitably, a lot of people will be waiting on the ground floor for quite some time. It's the same with a blockchain agreement (or 'consensus').

One solution to this problem is called 'Sharding'.

A good way to think of Sharding is like the formation of the United States.

The US has a collection of federal laws that are upheld all over the country. These are some of the most important laws like 'no drunk driving'. But because the country has so many citizens, it's hard to get people to agree on the smaller things. So the country was divided into 50 States.

These 50 States can make, update and uphold State laws without consensus from other States. In this way, things get done quicker and people are happier.

This is similar to how Sharding works on the blockchain.

A single blockchain has one set of rules for the whole network. These are some of the most important rules, like whether it's running Proof of Work or Proof of Stake. But because the network has so many members, it takes time for everyone's ledger to sync. So the network is divided into mini blockchains, or 'Shards'.

These Shards can process and update their part of the blockchain without consensus from the other shards. In this way, payments get processed quicker (because shards are working in parallel) and users are happier.

Shattered dreams?

The good thing about current blockchains is that attacking them (to spend the same money twice) is expensive. To do it, your computer needs to be as powerful as more than half the computers on network, which for a blockchain like Ethereum is usually thousands of computers.

With Sharding, there's only a few computers per shard so it's easier to attack. The good news is, this is harder to do in Proof of Stake than Proof of Work. Ethereum founder Vitalik Buterin has announced plans to switch Ethereum to Proof of Stake before using Sharding to scale the network.

We don't know if it'll work exactly as planned but it looks like Sharding holds huge promise for the future of speeding up blockchains.

Wanna know more? I recommend this video on Sharding.

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