Stale block is a term used when the same block is mined twice. In other words, it is called the situation where a block whose solution has been found is found again by another miner.
The block that is mined a second time is defined as stale, void, or invalid. A legacy block is a block whose data has already been processed by a miner. Since this block does not carry any value, the miner cannot benefit from the block reward.
Stale block situation can be experienced due to the protocols implemented in blockchain networks. Networks using the Proof of Work protocol may experience some delays and disruptions. As a result of the delays, the same block may be revealed by other miners. If the same block pops up again after the first block, the second block mined by the blockchain network is rejected.
Blockchain can be represented as a chain of data blocks. Each receives data from the previous one. Then the data from the closed block is forwarded to the next. The first will be called the ‘main block’ and the second ‘sub-block’. Since cryptocurrencies are mined on many devices, a master block can be the source for two sub-blocks created on different devices that are unaware of each other. But for the blockchain to be a whole network, two parallel branches should not be allowed. So the system discards one block and keeps the other. Thus, the choice of which block to reject from the two coexisting blocks emerges.
What is Proof of Work?
Proof of Work is a consensus mechanism for confirming and recording cryptocurrency transactions.
Every cryptocurrency has a blockchain, which is a public ledger made up of blocks of transactions. In Proof of Work cryptocurrencies, each transaction block has a specific hash. For the block to be confirmed, a crypto miner must generate a target hash equal to or smaller than that of the block. To achieve this, miners use mining devices that quickly generate calculations. The goal is to be the first miner to have the target hash. Because this miner is the one who can update the blockchain and get crypto rewards.
The benefits of Proof of Work (PoW) are as follows:
- High level of security
- It provides a decentralized method to verify transactions.
- It allows miners to earn crypto rewards.
The disadvantages of Proof of Work (PoW) are as follows:
- It is inefficient due to slow transaction speed and expensive transaction fees.
- High energy use.
- Mining often requires expensive equipment.
