Gate.io Blog What Is An Orphan Block?

What Is An Orphan Block?

01 January 08:00

An orphan block is a block that was successfully mined within a blockchain network but rejected by the network. The nodes accept blocks mined simultaneously and use both until one has more verified blocks generated from it than the other. The block with fewer succeeding blocks is discarded. “Orphan block” is a term used for the discarded block. They are also quite regular in decentralized blockchain networks, for example, Bitcoin… Learn more in the body of the article.

An orphan block is a block whose origin is unknown or nonexistent. Orphan blocks were created in older versions of the Bitcoin core software but are no longer in existence since the upgrade of the Bitcoin core software to version.0.10 in 2015. A block with an unknown parent block is no longer possible.

However, the term 'orphan block' is still in use in the crypto space when referring to mined blocks that were not integrated into the blockchain and got rejected. Technically the correct term for a discarded block is a 'stale block.' Most miners call the reward of such blocks 'orphaned,' which is believed to be why the name became synonymous with rejected blocks. Despite those blocks having a known origin, they are referred to as orphan blocks instead of stale blocks.

Orphan blocks are created when two or more miners mine and broadcast valid blocks to the network almost simultaneously. The network will be required to validate both blocks but add only one because although both blocks are validated, only one can be added to the chain. When two blocks are transmitted to the network nodes, each node decides —through a consensus mechanism— which block to integrate into the chain. Finally, when a decision is reached, the unchosen block is discarded and called an 'orphan block.'

In a blockchain, the longest line of blocks is added to the main chain. If two or more blocks were successfully mined at the same time, the block from which more blocks are generated is added to the main chain, and the block with fewer succeeding blocks is discarded and becomes an orphan block or a stale block.

WHAT ARE BLOCKS?

Blocks are data storage units used to store transactions on a blockchain network. They are usually linked to each other in chains forming the blockchain. A block is generated when miners solve certain complex calculations or algorithms storing transaction information and open a new block. The miner who does this receives a reward for the block. The procedure is repeated for each new block mined.

HOW ARE ORPHAN BLOCKS CREATED?
When a new block is mined, it contains information about the block from which it was mined and data of transactions. The child block is mined from the parent block. This means that the preceding block is called the 'parent block' while the succeeding block is called the 'child block.'. Only one can be initiated into the chain if two blocks are gotten from the parent block.

The network nodes are required to decide which block will get integrated into the blockchain by the Proof Of Work consensus mechanism. The rejected block is an orphan block (To be clear, the technical term is a stale block) because it was separated from the parent block. Any valid transactions contained in the orphan block are verified and added to the next block. The transactions get listed back into the blockchain.

ARE ORPHAN BLOCKS THE SAME AS STALE BLOCKS?
Orphan blocks, as explained earlier, are blocks with no information regarding the parent block or origin. Every block contains information about the previous block in it. For a block to exist without information about its parent block is rather impossible unless the blockchain has been tampered with. In the literal sense, any block without information on the parent block is an orphan block. On the other hand, stale blocks are blocks generated by the network and rejected. It is commonly called an orphan block, but they are entirely two different things.

WHERE ARE ORPHAN BLOCKS STORED?
Orphan blocks do not get integrated into the blockchain. They are temporarily stored in an 'orphan block pool' as it is called, because the information they hold is no longer significant to the network. For a literal orphan block, it can be integrated into the blockchain later if the parent block is identified and added to the chain.

In conclusion, orphan blocks are not common unless in the case of an attack on the blockchain. But stale blocks are relatively common and often occur on decentralized networks. It is estimated that 1 to 3 out of all the blocks mined in a day is stale blocks; while some networks have more, Bitcoin's daily average falls under 0.1.

Author: Gate.io Observer: M. Olatunji
* This article represents only the views of the observers and does not constitute any investment suggestions.
*Gate.io reserves all rights to this article. Reposting of the article will be permitted provided Gate.io is referenced. In all other cases, legal action will be taken due to copyright infringement.

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