Beginner’s guide to Ethereum finality

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Ethereum finality refers to the point at which a transaction on the Ethereum blockchain is considered irreversible and final. This is essential for understanding how the Ethereum network operates and the security it provides for users. Finality ensures that once a transaction is confirmed, it cannot be altered or undone, providing security and certainty for users of the Ethereum network. Without finality, there would be a risk of double-spending or other forms of fraud on the web.

Ethereum is a decentralized platform, and the way it reaches finality differs from other centralized systems. This article will cover the technical details of how finality is achieved in Ethereum. 

Understanding Ethereum Finality mechanism

The Ethereum network uses a consensus mechanism called Proof of Work (PoW). In PoW, a group of nodes, called miners, compete to solve a complex mathematical problem. The first miner to solve the pain gets to add a new block to the blockchain, and in return, they are rewarded with a certain amount of Ether. 

This process ensures the integrity of the blockchain by making it difficult and costly for any one miner to take control of the network. This is the same mechanism Bitcoin uses and is the most widely adopted mechanism of all.

However, other consensus mechanisms have been developed and used in other blockchain networks. One of the leading alternative consensus mechanisms is Proof of Stake (PoS). Instead of miners solving complex mathematical problems, validators are chosen to create new blocks based on the amount of cryptocurrency they hold and are willing to “stake” as collateral. 

This approach is less energy-intensive than PoW because it does not require large amounts of computational power. Another alternative is Delegated Proof of Stake (DPoS), which allows token holders to vote for “delegates,” which will validate transactions and create new blocks. These mechanisms can achieve faster transaction processing times and greater scalability. But the security of PoS and DPoS heavily depends on the excellent behaviour of validators.

How Ethereum finality is achieved

In Ethereum, finality is achieved through a process of block confirmations. When a block is mined, it is broadcast to the rest of the network, and other miners begin working on the next block. As each new block is added to the blockchain, the previous block becomes more challenging to change or reverse. 

This process continues until a certain number of confirmations are reached, at which point the block is considered final, and the transaction is considered irreversible. The number of guarantees needed for finality is determined by the specific use case and can vary depending on the application.

It’s also important to mention the concept of “uncles” and their impact on Ethereum finality. An “uncle” block refers to a valid block that is not included in the main blockchain but still gets a reward for the miner. These blocks are typically created when two miners find a block at the same time, and the network chooses one to be added to the main blockchain while the other becomes an “uncle” block. 

Uncles blocks help to provide a measure of security to the network by incentivizing miners to continue working, even if their block is not chosen. However, it is worth noting that if a miner finds more than six uncles, it is not rewarded for them. Therefore, uncles do not impact Ethereum finality directly, but they increase the network’s security and make it more difficult for a miner to take control of the network.

The potential impact of Ethereum 2.0 on finality

Ethereum 2.0, also known as Serenity, is the next planned upgrade for the Ethereum network. One of the main changes with Ethereum 2.0 is a shift from the current Proof of Work (PoW) consensus mechanism to a Proof of Stake (PoS) mechanism. 

Under PoS, instead of miners competing to solve mathematical problems, validators are chosen to create new blocks based on the amount of Ether they hold and are willing to “stake” as collateral. This approach is more energy-efficient than PoW leading to faster transaction processing times and greater scalability for the Ethereum network.

The shift to a PoS consensus mechanism in Ethereum 2.0 has significantly impacted finality in the network. Under the PoS mechanism, the finality is reached when 2/3 of the validators have voted for a block, and a block is considered final after a certain period. The process of block confirmations is different under PoS. With the implementation of PoS, the risk of forks and the need for more guarantees is reduced. In addition, the introduction of shard chains in Ethereum 2.0 improves scalability, which in turn leads to faster finality for transactions. 


Finality in Ethereum is an essential concept for understanding how the network operates, and it provides a crucial layer of security for users. The Ethereum network continues to evolve and improve, and this guide has provided a solid foundation for understanding the technology behind Ethereum finality.

We’ve explored the essential concept of Ethereum finality and its significance for users of the Ethereum network. We’ve delved into the inner workings of the Ethereum blockchain and explained how transactions reach finality through block confirmations. One of the key takeaways from this article is understanding the Proof of Work (PoW) consensus mechanism used by Ethereum, how it differs from the alternative Proof of Stake (PoS) and its agency, as well as the role of “uncles” in maintaining the security of the network. Finality in Ethereum is an essential concept for understanding how the network operates, and it provides a crucial layer of protection for users.

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