2: What is blockchain?
At its core, blockchain was created to solve the issue of trust.
Specifically, to solve the Byzantine Generals Problem. Here's the problem:
A group of generals want to invade a city. The only way they can capture the city is if they all attack at the same time BUT they cannot communicate directly, they can only go through messengers that are unreliable AND some of the generals could be unreliable. So, how do they know when to attack?
Think of the game "telephone." When you have played in the past, how often did the correct message get through the circle? I'm guessing very little...
Essentially, blockchain makes sure that message gets across.
AND, the solution to the Byzantine Generals Problem was presented through the Bitcoin white paper. Bitcoin is the first blockchain.
Let's formally define a blockchain:
A blockchain is: a digital, decentralized, immutable, ordered, append-only, verifiable ledger (more correctly an ordered data structure because the data is not organized in a table like a ledger is) of information. Often, we see this information being store as financial information.
Wanna know a fun fact? The longest running blockchain example (in the real world) is The New York Times. Let's break it down...
Decentralized*: every person can own the NYT, it doesn't just exist in one place. However* their clearly are people in charge of the NYT and what is printed, etc.
Immutable: Once the NYT is printed, it's printed; there is no changing it.
Ordered: Each NYT is dated to very clearly put the information, the editions, in order.
Append-only: You can't add a new edition before an old one.
Verifiable: Theoretically, every person could hold their own copy of every single NYT and verify the information in them.
Now, you might be thinking, ok, blockchain sounds cool, but how does any information get added to it if no one is in control?
The answer lies in consensus protocols. Bitcoin uses Proof of Work (PoW). Ethereum uses Proof of Stake (PoS). Ethereum used PoW until September 15, 2022. We will dive into these in the next article.
Originally published on: April 16, 2023
