The hype around blockchain is massive. To hear the blockchain hype train tell it, blockchain will now:

Solve income inequality Make all data secure forever Make everything much more efficient and trustless Save dying babies What the heck is a blockchain, anyway? And can it really do all these things? Can blockchain bring something amazing to industries as diverse as health care, finance, supply chain management and music rights?

And doesn’t being for Bitcoin mean that you’re pro-blockchain? How can you be for Bitcoin but say anything bad about the technology behind it?

In this article, I seek to answer a lot of these questions by looking at what a blockchain is and more importantly, what it’s not.

What is a blockchain? To examine some of these claims, we have to define what a blockchain is and herein lies a lot of the confusion. Many companies use the word “blockchain” to mean some sort of magical device by which all their data will never be wrong. Such a device, of course, does not exist, at least when the real world is involved.

So what is a blockchain? Technically speaking, a blockchain is a linked list of blocks and a block is a group of ordered transactions. If you didn’t understand the last sentence, you can think of a blockchain as a subset of a database, with a few additional properties.

The main thing distinguishing a blockchain from a normal database is that there are specific rules about how to put data into the database. That is, it cannot conflict with some other data that’s already in the database (consistent), it’s append-only (immutable), and the data itself is locked to an owner (ownable), it’s replicable and available. Finally, everyone agrees on what the state of the things in the database are (canonical) without a central party (decentralized).

The hype around blockchain is massive. To hear the blockchain hype train tell it, blockchain will now:

Solve income inequality Make all data secure forever Make everything much more efficient and trustless Save dying babies What the heck is a blockchain, anyway? And can it really do all these things? Can blockchain bring something amazing to industries as diverse as health care, finance, supply chain management and music rights?

And doesn’t being for Bitcoin mean that you’re pro-blockchain? How can you be for Bitcoin but say anything bad about the technology behind it?

In this article, I seek to answer a lot of these questions by looking at what a blockchain is and more importantly, what it’s not.

What is a blockchain? To examine some of these claims, we have to define what a blockchain is and herein lies a lot of the confusion. Many companies use the word “blockchain” to mean some sort of magical device by which all their data will never be wrong. Such a device, of course, does not exist, at least when the real world is involved.

So what is a blockchain? Technically speaking, a blockchain is a linked list of blocks and a block is a group of ordered transactions. If you didn’t understand the last sentence, you can think of a blockchain as a subset of a database, with a few additional properties.

The main thing distinguishing a blockchain from a normal database is that there are specific rules about how to put data into the database. That is, it cannot conflict with some other data that’s already in the database (consistent), it’s append-only (immutable), and the data itself is locked to an owner (ownable), it’s replicable and available. Finally, everyone agrees on what the state of the things in the database are (canonical) without a central party (decentralized).