All you need to know about Ethereum blocks
Ethereum blockchain is a distributed environment for data operation and interaction with the software code of decentralized applications, the functioning and security of which is provided by cryptographic rules. This is a platform that allows you to perform asset transfers between network members and create dApps based on smart contracts. The blockchain is built from blocks containing transactions. Let’s figure out what the blocks are made of and what types they can be.
Blockchain: the chain of blocks
On average, every 10 minutes a new block appears on the Bitcoin network, the Ethereum network deals with it in only 14 seconds. Each block has information about previous block. That’s what makes it possible to build a chain of blocks — an index. You can compare it with a numbered list or an Excel table. There are no skips. Number 1 is always followed by number 2, and number 3 is followed by 4.
Each node in the network is connected to others and constantly exchanges information with them. Let’s assume that the last block in a cryptocurrency network has number 100. All world’s miners solve the same problem and look for the solution of block 101. As soon as they find it, the miner (or the mining pool) sends the solution to the network through its node. Within a few seconds, and usually even milliseconds, all nodes in the network receive information about the new Block 101. They check that the block is true, there is no cheating in it, and then they wait for block 102.
The question is: what happens if two miners find the solution to block 101 at the same time? For example, there are 100 nodes in the network. Miner A found the block solution a little earlier and managed to transmit information about the block to 60 nodes. Miner B did the work later and managed to tell about the found solution of the block only at 40 nodes. Does this mean that A is good and B is not? No, it doesn’t. Let’s consider these nuances in more detail on the example of BTC and ETH coins.
Block types in Bitcoin network
Ten minutes per block is the average time, in fact it can be a few seconds or even a few hours. Suppose the blocks are moving fast, or the nodes do not communicate with each other very fast.
Miners A and B found the solution to block 101 at about the same time. 60 percent of the nodes received a new block from Miner A, 40 percent from Miner B. At this point, both of these blocks are absolutely true, legal, valid as you like. Immediately after that, the miners that listened to Miner A found 2 more blocks, while the miners that listened to Miner B found 3 more blocks.
So how do you decide whose chain is right? The solution is simple. The followers of Miner B have a longer chain, so it is correct. The followers of Miner A, unfortunately, worked for nothing. They’ll get nothing for their blocks.
Remember that we have an index, a numbered list? Well, the result is block 101, which was found by Miner B, and then the next 3 blocks found by his followers at numbers 102, 103 and 104. The block that found Miner A didn’t make it to the index. He was left without his father, he was “cut off”, so this block is called an Orphan. The good news is, he’s got two kids left, blocks that were found behind him. Bad news: there is no sense in these blocks, they are called Stale.
In fact, of course, it’s unlikely that the nodes will wait that long. Already at presence of the next block 102 after the disputable block 101 all the cryptocurrency network will switch to this branch and will reject another.
To sum up, Bitcoin has the following blocks:
- Normal (valid) block, which is included in a chain of Bitcoin blocks. The miner who finds it gets a reward.
- Orphan — a block that has no predecessor (parent) in the chain of Bitcoin blocks. For Orphan block the miner receives nothing.
- Stale — a block that is not included in the chain of Bitcoin blocks because its predecessor is an Orphan block. In other words, the chain starts with the orphan block. Miner gets nothing for the Stale Block.
Block types in Ethereum network
The average block time in Ethereum network is much less than that of Bitcoin: 14 seconds versus 10 minutes. Obviously, the problem of Orphan and Stale blocks should occur much more frequently, which means that the wasted work of miners should be great in theory. Fortunately, in practice it’s different. The developers of this cryptocurrency have implemented the so-called GHOST protocol (Greedy Heaviest Observed Subtree).
The meaning of GHOST is simple — miners who find Orphan and Stale blocks are also rewarded, although the reward size is less than the amount for normal blocks. Such blocks in the Ethereum network and some other cryptocurrencies began are called Uncle.
Uncle blocks also solve the problem of network centralization. If they didn’t exist, the situation would be strange. With such a small time of a block, a large pool would work much more efficiently and simply kill small competitors who would get information about new blocks for a long time. In their turn, they would have mined useless Orphan/Stale blocks without end.
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