Don’t let the technical jargon used to describe “blockchain” scare you. Simply put, a blockchain is a database. It is also not a particularly complex one; with little effort, you could make it in a spreadsheet.
These databases have a few oddities. The first is the append-only nature of blockchains. This implies that you can only add information; you cannot just click on a cell to delete or modify information that has already been entered.
The second is that every database entry (also known as a block) is cryptographically linked to the entry before it. In plain English, every new entry is required to have a copy of the previous one’s digital fingerprint or hash.
That’s all, then! As a result of every fingerprint pointing back to the previous one, a chain of blocks is created. Or, as the hipsters prefer to refer to it, a blockchain.
A blockchain is immutable; if a block is changed, the fingerprint is also changed. Additionally, the following block is altered because that fingerprint is present there as well. Since the fingerprint of that block is… well, you get the point. The result is a domino effect where any change is apparent. Nothing can be changed without everyone noticing.
Is that it?
Underwhelmed? Fair enough. The invention shown here is not some clumsy Google Sheets substitute. It is the ability for everyone to download blocks from other network users in order to create exact replicas of the blockchain on their computers. The program we previously described accomplishes this.
Let’s say the program is being used by you, and your buddies Alice, Bob, Carol, and Dan. I wish to send five coins to Bob, you might say. You, therefore, communicate that directive to everyone else, but Bob doesn’t receive the coins right now.
Carol can choose to gift Alice five pennies at the same moment. Additionally, she broadcasts her directive to the network. A player can put all of the pending instructions together at any time to form a block.
What prevents someone from cheating if anyone can make a block?
You must find it incredibly appealing to make a block that reads, “Bob pays me a million coins.” Or to start making transactions using the money you don’t own to start purchasing Lamborghinis and fur jackets from Carol.
That’s not how it works, though. The system stops you from using money that you shouldn’t be able to use thanks to some cryptography, game theory, and something called a consensus algorithm.
