Introduction

Why does blockchain need consensus?

The blockchain is a distributed, decentralized ledger. Each node in the blockchain network keeps its own copy of the ledger

Any node in the network can create a block. Control over block creation gives control over the ledger, and this breaks decentralization

Consensus algorithms decide who should create the next block. These algorithms must be able to be run in a decentralized fashion

Example

Imagine you and your friends are playing a game where you have to keep track of all the scores. Instead of having one person in charge of keeping the scores, you decide that everyone should have their own copy of the scoresheet. This way, if someone tries to cheat or change the scores, everyone else can catch them.

In the world of blockchain, this idea of everyone having their own copy of the scoresheet is called decentralization. But here's the challenge: if everyone can create a new entry on the scoresheet, how do you decide whose entry is valid? This is where consensus algorithms come in. They are like rules that everyone follows to agree on who gets to add the next entry to the scoresheet.

Consensus algorithms make sure that the blockchain stays decentralized and secure. They ensure that no one person has too much power and that everyone agrees on the valid entries. It's like having a fair and trustworthy referee in your game.