Kaspa - What is the Nakamoto Consensus? What are its Advantages and Disadvantages?
Consensus refers to an agreement or compromise.
When you aim to create a decentralized system, the first thing you need to address is connecting actors in different locations with each other.
All actors must come to a consensus on the actions taken.
When a transaction occurs on a blockchain, nodes record this transaction and communicate with other nodes, saying, "I've recorded it, now it's your turn."
However, sometimes there are communication breakdowns or intentional disagreements among nodes.
For example, when Ali sends 1 $BTC to Mehmet, Melik records it and sends the block to Selim and Turgut for them to record.
If another transfer occurs before the block reaches Selim and Turgut, and Melik records that too, it creates chaos. Hence, communication needs to be fast.
Indeed, Selim and Turgut could create disagreements by saying, "We hate Ali, so even though he sent 1, we will record it as 5."
Or, Ali and Turgut could conspire and falsely claim to have sent each other 100 $BTC even though they never had such transactions.
In a Distributed Ledger System (DLS), various undesirable occurrences like this can take place. Malicious individuals, by gaining the majority, may take unfair or malicious actions in line with their interests.
All the problems I have mentioned so far have a general definition in the computer world:
Byzantine Generals Problem
or
Byzantine Fault Tolerance
Consider a fortress and 4 Byzantine generals attacking it. Each general is at a distant location from the others, but they need to coordinate their attacks in an organized manner for the fortress to fall.
If the messenger carrying messages between the generals delivers the wrong message, if something happens to the message along the way, or if one general does not comply with the message, coordination breaks down, and the success rate decreases.
Such a consensus mechanism is needed that ensures all generals coordinate together.
In summary, a consensus mechanism that completely prevents Byzantine generals from making mistakes is still being developed.
In 2008, Satoshi Nakamoto addressed the resilience to the Byzantine Generals' Problem by publishing a paper, introducing a high-resilience consensus - Bitcoin
