What is POW ?
Ethereum, like Bitcoin, currently uses a consensus protocol called Proof-of-work (PoW). This allows the nodes of the Ethereum network to agree on the state of all information recorded on the Ethereum blockchain and prevents certain kinds of economic attacks.
WHAT IS PROOF-OF-WORK (POW)?
Proof-of-work is the mechanism that allows the decentralized Ethereum network to come to consensus, or agree on things like account balances and the order of transactions. This prevents users from “double spending” their coins and ensures that the Ethereum chain is tremendously difficult to attack or manipulate
PROOF-OF-WORK AND MINING
Proof-of-work is the underlying algorithm that sets the difficulty and rules for the work miners do. Mining is the “work” itself. It’s the act of adding valid blocks to the chain. This is important because the chain’s length helps the network follow the correct Ethereum chain and understand Ethereum’s current state. The more “work” done, the longer the chain, and the higher the block number, the more certain the network can be of the current state of things.
HOW DOES ETHEREUM’S PROOF-OF-WORK WORK?
Ethereum transactions are processed into blocks. Each block has a:
- block difficulty — for example: 3,324,092,183,262,715
- mixHash — for example:
0x44bca881b07a6a09f83b130798072441705d9a665c5ac8bdf2f39a3cdf3bee29 - nonce — for example:
0xd3ee432b4fb3d26b
This block data is directly related to proof-of-work
The work in proof-of-work
The proof-of-work protocol, Ethash, requires miners to go through an intense race of trial and error to find the nonce for a block. Only blocks with a valid nonce can be added to the chain.
When racing to create a block, a miner will repeatedly put a dataset, that you can only get from downloading and running the full chain (as a miner does), through a mathematical function.
Proof-of-work and security
Miners are incentivised to do this work on the main Ethereum chain. There is little incentive for a subset of miners to start their own chain
The objective of proof-of-work is to extend the chain. The longest chain is most believable as the valid one because it’s had the most computational work done. Within Ethereum’s PoW system, it’s nearly impossible to create new blocks that erase transactions, create fake ones, or maintain a second chain. That’s because a malicious miner would need to always solve the block nonce faster than everyone else.
