A surprisingly simple explanation of blockchain for normal people

What blockchain is and why it’s about to change everything.

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This story is about trust

Trust. Can you trust me? What makes you sure?

Trust between people is what makes everything possible. If we don’t have trust, we need to build it through legal, commercial and financial systems. You want to buy my house, sure, but unless we’re related you’ve already called your lawyer.

Blockchains can revolutionise trust

Blockchains are set to change everything we know about trust. They are the first proven way to establish trust through technology, rather than human systems like banking or law.

Blockchains were invented to solve the problem of how you make a global currency without being a bank. Or even trusting banks. Their invention made Bitcoin possible, and all the other cryptocurrencies that followed. Bitcoin proved that blockchains work.

Trusting blockchain beyond Bitcoin

Now we think that blockchain can solve many more of our trust issues. Things like how can you prove who you are to someone by email, or how can you stop your online work being copied a million times.

Blockchain has the potential to bring worldwide trust to the worldwide web. And that’s what’s getting everyone excited. It’s why we’re seeing such an explosion of new startups using blockchain (or saying they’re using blockchain).

What is blockchain?

A blockchain is a new way of storing and sharing information between people who need to trust each other.

You can put any information in a blockchain and once you do it’s there forever. Like properly forever. You can’t change it or delete it, and neither can anyone else. Ever.

And if the blockchain is stored like Bitcoin’s blockchain, you can’t delete it. No one owns it and there’s no one in charge. So there’s no one you can persuade to take the blockchain down. Even if you’re a government, nuclear power or the FBI’s most-wanted hacker, there’s just no way of taking it down. Ever.

Blockchains are forever - 1. Why can’t I delete my information?

Blockchains store your information in a block with other information. This is all encrypted in computer code.

The blocks of information are then woven together using more clever coding. Each new block makes a link with the one before. The blocks are linked one after the other in a continuous chain, hence ‘blockchain’.

If you try to change or delete any of the information in a block, the link will break.

Even a change as tiny as adding a comma or moving a digit will break the link. And if a link breaks, the blockchain will fix itself by restoring the information to how it previously was. You just can’t make a change. Information in a blockchain is forever.

Photo by Markus Spiske

Blockchains are forever - 2. Why can’t I delete the blockchain?

You can’t delete a blockchain like Bitcoin’s blockchain because there’s no one place to delete it from. It’s stored and simultaneously updated on thousands of connected computers owned by thousands of different people all over the world.

To delete or hack this kind of blockchain you’d have to attack thousands of computers at the same time. Leave just one copy on one far-flung computer, and the blockchain will be restored to how it was.

Blockchains don’t need to be stored like this. But the most revolutionary ones are.

Everyone in a blockchain can see everything

So if I write something on a blockchain I can trust that no one can delete, change or move that information. What’s more, in blockchains like Bitcoin’s, anyone can see the information being added to it, as it happens.

The information you see is encrypted, but there is a huge amount of transparency in the system. Ask your bank to see all its financial records to appreciate the big difference. This transparency is another level of trust.

Over 10,000 computers or 'nodes' in Bitcoin's network. Image: Bitnodes

The blockchain revolution is coming, the only question is when

Bitcoin proved that a blockchain can create enough trust to make a global currency without the backing of governments or banks. Technologists are now looking to use blockchain to revolutionise trust across every industry you can think of. Some exciting applications are in safeguarding intellectual property, automating legal contracts, preventing food and pharma scandals with fail-safe tracking, and proving the ownership of our personal data (sorry Facebook).

The big question is when this trust revolution will happen. The hype about the technology is outrunning today’s reality. Most projects other than Bitcoin and some financial applications are in their earliest stages. But we now know we can establish trust through technology, and a seismic change is on its way.