Many people hear “consensus” referred to when there is a fork happening in the network, which is accurate, but beyond that context, consensus is what’s happening every day, within a given blockchain. The word “consensus” very specifically refers to users of that network agreeing to (coming to consensus on) what rules to run for their network.
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Consensus algorithms to a blockchain are like the inner mechanical workings of a car. It’s the system in place that choreographs the running of the vehicle. In the case of blockchain, it’s how all the nodes come together to verify that transactions in the network are accurate, thus honest; it’s the intangible mechanics of rules built into the blockchain to make sure it runs in a secure, effective and efficient way. And, like with a car, you’d much rather have one that’s built to run more like a Mercedes Gullwing rather than a Pontiac Fiero.
Also like with cars, inspecting the inner algorithms or mechanics of each blockchain takes a lot of technical knowledge. I’ve extensively studied Proof of Work, which is the consensus protocol that runs the Bitcoin network, but I have yet to dissect the consensus mechanisms that other blockchain projects have evolved into, such as Proof of Stake, Proof of Activity, Proof of Burn, Proof of Capacity, Proof of Elapsed Time, etc. As I more intimately explain each crypto project, this will be done.
For now, I can report that much like with Henry Ford’s Model T, Bitcoin’s Proof of Work is a pioneer of its time, and front-runner in its industry. Bitcoin’s original protocol is constantly undergoing attempts of improvement in the form of network forks, where users are not in agreement as to the best rules for running the network. Although arguably damaging to Bitcoin’s perceived integrity, these disagreements (lack of consensus) keep Bitcoin’s Proof of Work relevant and evolving. Bitcoin is the original vehicle for blockchain technology, and its head start has helped it form a more secure network and position in the market. We shall see how its consensus protocol stacks up, over time.
Feel free to consume the below linked YouTube video for more context. Here is the link to a more descriptive document on Bitcoin’s Proof of Work/SHA256 protocol (scroll to the section titled: “In-Depth Info on Bitcoin’s Consensus Protocol”). The document makes Proof of Work understandable, even if you are not a computer scientist.