The Blockchain For Dummies Guide — Part 2
RECAP: In Part 1, we talked about databases in their current form and some inherent problems they present in maintaining their health and accuracy. We also talked about the Byzantine General’s Problem where we don’t know if messages sent to a distributed database are both received and accurate.
So right now, it seems we’re shit out of luck on these problems unless we can find a different solution.
Enter Blockchain
So now we know how valuable databases are to our digital lives and we also understand some problems that plague them, what is a blockchain and how is it different than a regular database?
Well first off, its important to clarify that a blockchain is a database, its just a special type of database.
So what makes it so special and why is it needed in systems like Bitcoin to track the movement of digital assets, like a digital currency?
Actually Bitcoin can be separated into smaller components and thought of like this:
Bitcoin = A Digital Asset + Blockchain + Cryptography
But before we talk about digital assets and *gulp* cryptography, let’s focus on the blockchain because its the foundation through which the other two interact.
Let’s say I have a box of eight digital crayons. In this box, we have the standard color set you’d remember from your childhood in a Crayola crayon box:
Now if you recall from your childhood, these crayons always came in a certain order in the box: black was next to brown which was next to purple, etc.
Now if someone came to us and said “This is the logical order of crayons in a Crayola crayon box,” we’d know this to be true from our own experience. But what if we wanted to guarantee that ordering to someone else that has never seen a box of Crayola crayons? We can do that by creating a crayon blockchain:
Same set of crayons, but with a key difference: every crayon has a star on it that refers to the color of the crayon that precedes it.
NOTE: Black is a special crayon, known as the genesis. Since it’s the first crayon, it has no preceding crayon and thus just refers to nothing.
That’s all a blockchain is! You’re now a blockchain expert. Wasn’t that easy?
Blockchain can get a lot more complicated, but at its core this is really all that’s happening in complicated protocols like Bitcoin.
A blockchain is just a database where each entry into the dataset refers to the previous entry.
The reason why a blockchain is different than a normal database is because it gives us a guarantee on the order of the data.
So in the case of a distributed blockchain database, we can look at each copy of the database and know whether the data is correct or not because the data is chained together.
In our crayon example, if a crayon went missing, the next crayon would still be referencing the missing crayon, so we’d know immediately that something was wrong.
In the case above, we can see that the green crayon has gone missing from our crayon data set, but we can see that immediately because the yellow crayon is referencing something that is no longer there.
So that’s all a blockchain is! We’re ready to go and just start using this cool new thing, right?
Well not yet, we still haven’t solved our Byzantine General’s Problem we talked about in Part 1. How do we communicate the proper order of the crayons to the rest of the network and how does the network agree on which order is correct?
In our generals problem, let’s say that the generals agree to attack if and only if they can agree on the proper order of our crayon set. How do the generals:
- Agree upon the proper order of the crayons?
- Know that an agreement has been reached between them?
- Know that they aren’t wrong about #1 or #2?
This leads us into another problem that blockchain solves, the problem dealing with network consensus.
How Do We Know? How Do We Know We Know? And How Do We Know We Aren’t Wrong?
In Part 3, we’ll go into how the blockchain protocol solves the problem by achieving a consensus in the network and how our generals can agree on whether to attack the city or not.
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