If you are interested in cryptocurrency mining or are already mining cryptocurrency, you most likely know what a block is. For those who do not know, a block is part of the blockchain and holds a collection of transactions. These blocks are formed and added to the blockchain by miners, and with this a record is maintained of all the transactions ever made on let’s say the Bitcoin blockchain.
The majority of people are not aware of the fact that there are different sorts of blocks in blockchain technology. However, for miners for example, it can be useful to have an understanding of the different types of blocks since it can help them understand the effect on expected income. Do not be alarmed though. Data from Blockchain.com, a bitcoin block explorer-service, reports that Orphan blocks for instance – one of the block types that does not lead to a block reward – hardly ever occur.
So, different sorts of blocks exist and they all have a specific purpose in blockchain technology. Let’s have a look at the block types.
As the name implies, these blocks are orphaned and therefore do not have a parent. In other words, they are no longer part of the longest chain (which is the one used). Although these blocks are verified, they are still rejected by the chain due to a time lag in the acceptance of the block. Remember that only the first miner that successfully finds a new block gets his block added to the blockchain and receives a block reward. The Orphan block, which got rejected due to being late, will exist isolated from the blockchain and therefore will not lead to a block reward.
Contrary to popular belief, Stale blocks and Orphan blocks are not the same. As mentioned in the previous paragraph, Orphan blocks are not part of the longest and their parent block is unknown. Therefore they cannot be validated and will not be accepted by the network. A stale block is a successfully mined and valid block but is not included in the blockchain being used. Basically, stale blocks are old blocks that are already mined. For those who do not know, if the blockchain network is dealing with two different versions of blockchain, only the longest chain will survive. As with Orphan blocks, Stale blocks do not lead to a block reward. The image below visualizes an Orphan block as well as a Stale block.
Yes Uncle blocks, we did not come up with that name. Uncle blocks are the Ethereum equivalent of Orphan blocks on the Bitcoin blockchain. Mind you, Uncle blocks also exist on blockchains that are based on Ethereum. Like Orphan blocks, Uncle blocks get rejected by the blockchain network.
However, miners do get rewarded for Uncle blocks for two reasons. The Ethereum protocol encourages miners who find these blocks because it stimulates the degree of decentralization. As opposed to the Bitcoin blockchain where the longest chain is leading, here the heaviest chain is leading. The creation of Uncle blocks make a blockchain heavier. The Ethereum protocol works with the heaviest chain and Uncle blocks instead of the longest chain, because the faster pace of creating transactions on the Ethereum blockchain would lead to significantly more Orphan blocks. On top of this, because a larger amount of effort is put in, it improves the security of the blockchain. Miners that produce Uncle blocks are rewarded 6,25 ether (ETH).
We hope that this article gives you more insight in the extraordinary blocks that are mined and what it means for block rewards.