Let’s break it down –
Did you think a block was a block was a block? Actually, in the cryptocurrency and blockchain space, there are several different kinds of blocks. Although not everyone understands what they are nor what they mean. Hopefully, by the time this article is read and absorbed, the reader will have a better understanding of the different block types and the functions each serve within blockchain-based protocols.
Blocks in Bitcoin blockchain:
- The Genesis Block begins the blockchain.
- The (Valid) Block is a block that gets included in the Bitcoin blockchain. A miner that finds it gets rewarded.
- The Orphan Block is a block that doesn’t have a predecessor/parent. Miners don’t get rewarded for orphan blocks.
- The Stale Block (Orphan’s offspring) is a block that doesn’t get included in Bitcoin blockchain because an orphan block precedes it. Miners don’t get rewarded for stale blocks either.
Genesis block – Providing the foundation for every blockchain-based protocol is the Genesis Block. The Genesis Block is the FIRST block on which the entire blockchain is built. The creator of Bitcoin left a message on Genesis Block that reads: “The Times 03/Jan/2009 Chancellor on brink of second bailout for banks”. It seems fitting words for the Genesis Block of Bitcoin; however, its interpretation is undoubtedly open. A Genesis Block is the first block (block number 0) in a blockchain and is the only block in a blockchain that does not have a valid reference to a previous block. The Genesis Block has no transactions.
Orphan Blocks were valid blocks that met all the requirements to be added to the blockchain but still rejected. Why is this? Orphan Blocks occur when two or more miners produce a block at similar times. Latency can be an issue, especially if the miners are vast distances apart. Nodes serving the area closest to the miner will pick up this miner’s submission that is closer to them. In these cases, the miner with the most “proof of work” wins the reward, and the other block(s) become “Orphan Blocks.” How often does this happen? More times than some care to mention.
Blockchain.info keeps track of all the orphaned blocks, and they show this occurs as often as one to three times daily. Since a new block is mined on average every ten minutes, and 144 block rewards paid out daily, this would also mean that Orphan blocks happen over 1% daily.
It is not the block that is orphaned
These “Orphan Blocks” topics are confusing because of the wording, even for seasoned Bitcoin miners. This incorrect terminology likely began because these “stale blocks” referred to as orphaned blocks in the Bitcoin reference client. In actuality, orphaned blocks are not orphans as they DO have parents in the form of the previous blocks added to the blockchain. What part IS orphaned then? It is the payout that is orphaned.
From the image above, you can see that two blocks were created and sent to the Bitcoin network on the same date and at very similar times 13:44:19 PM and 13:44:31 PM by two separate mining pools: AntPool and SlushPool. As you can see, AntPool expended more proof-of-work in creating its block, so it is chosen over the block created by SlushPool. Notable, too, is that even though the block is valid according to the consensus rules of Bitcoin protocol, miners don not get the reward for the Orphan Blocks.
Stale Blocks often referred to as “offspring” of Orphan blocks. Most often, when people say “orphan block,” they mean a Stale Block. A Stale block is a well-formed block that is no longer part of the blockchain. The Block Reward is no longer spendable on the blockchain; therefore, whoever mined that block does not get the reward (or the transaction fees). Often two miners find the “solution” to a mathematical puzzle and submit their blocks to be added to the blockchain at the same time. In this case, the miner with the longest valid chain wins the reward. The one(s) with the least amount of Proof of Work, must discard that block known as a “Stale Blocks,” and resume working on another block.
Blocks in the Ethereum blockchain
Uncle Blocks associated with the Ethereum protocol is equivalent to Orphan blocks on the Bitcoin Network. There is a slight difference, however. Uncle Blocks are still valid blocks created and submitted to the blockchain and rejected by the network. However, unlike the orphan blocks where miners are not rewarded for them, miners DO receive rewards for creating an Uncle block. For a valid block successfully mined on the Ethereum network, miners are rewarded with three Ether. Conversely, the production of an uncle block gives a reward of 2.625 Ether
Ethereum average block-find time is about 14 seconds. Since Orphan and stale blocks are expected to be encountered more often than in Bitcoin networks, miners could waste more time. Thanks to a protocol called GHOST protocol (Greedy Heaviest Observed Subtree) implemented by Ethereum developers, this doesn’t happen.
The concept of GHOST protocol: Miners who find Uncle Blocks do get rewarded. However, the reward is not as much as for a standard block. In Ethereum and other Daggar-Hashimoto cryptocurrency networks, these blocks are called Uncle Blocks.
Uncle Blocks resolve the problem of network centralization. With the shortened block time, a significant mining pool would work much more effectively and squeeze smaller competitors out. The smaller groups would receive information on new blocks much too slowly and would be creating a considerable amount of useless blocks.
Types of blocks in Ethereum Blockchain:
- The Genesis Block begins the Ethereum blockchain.
- A Valid Block is a block successfully included in the Ethereum blockchain. Miners of these blocks get rewarded for their work.
- Uncle Blocks correspond to Orphan and stale blocks in the Bitcoin network. Uncle Blocks like Orphan and Stale blocks are not included in the main blockchain, and miners get lower rewards for Uncle blocks than for Valid blocks.
Uncle Block Rewards in Ethereum Network
Ethereum will allow seven nested levels of Uncle Blocks, which would be the same as one orphan block and six stale blocks in Bitcoin’s Network. In the Ethereum blockchain, the uncle block reward is figured with this formula:
([Uncle block number] + 8 – [Block number]) * [Ethereum reward] / 8
So, if the normal block reward is 3 ETH, the Uncle reward would be 1/8th less.
The reward for the very first uncle block is 2.625 ETH, for the second one – 2.25 ETH, then 1.87 ETH, and so on until 0.375 ETH. Uncle chains are not likely to go on for very long. After a couple of Uncle Blocks, a miner node will generally abandon the wrong chain and go to the main mining chain.
You can check out Ethviewer to see Ethereum mining. You can see in real-time the main chain and uncle chains being produced.