What Is an Orphan Block?

In blockchain terms, orphan blocks are blocks with less proof than another block, resulting inܫ the block with more proof being accepted by the blockchain. These blocks are usually created due to network lag between nodes. However, because most minable blockchains are now consolidated to mining pools with very low latencies and updates to blockchain programming have addressed their creation, they are very rare.

History of Orphan Blocks

A blockchain consists of a series of blocks—files that store details of the various transactions occurring on the blockchain network. During the standard mining process, miners produce new blocks and attempt to generate a hash that meet﷽s the network's target difficu🐼lty value.

The first miner who successfully generates a winning hash is entitled to the 澳洲幸运5官方开奖结果体彩网:block reward and has their block added to the blockchain. The process of proposing blocks and trying to add them to the blockchain the🍸n repeats.

This process of generating sequentially linked blocks creates a 澳洲幸运5官方开奖结果体彩网:blockchain where blocks receive information—called the block header—from the bꦍlock that preceded them. The block that received the block header is called the child block, and the block that had its header transferred is called the parent block.

Old Definition

A block without a parent block is one with an incomplete 澳洲幸运5官方开奖结果体彩网:block hash. The block hash is an encrypted number and a snapshot of the complete blockchain at the moment the block was created. Parent block information 🌠would be included in this hash, so an orphan block would be a strange occurrence in a network that relies on validation and verification of all preceding blocks.

However, a block was occasionally proposed that was missing its parent's header, so it could not be processed. This block was called an orphan block because it had no verifiable parent block.

Current Definition

The Bitcoin blockchain was updated in 2015 to prevent actual orphan blocks from occurring, so they are no longer created. Orphan blocks are now considered to be blocks that do not have enough proof to be accepted. The way this works is that occasionally a block is validܫated and added to the chain at the same time another valid block is. These two blocks are used to create more blocks, causing two chains to emerge. Eventually, one of the chains will have more proof, and the other chain will be discarded. The blocks of the shorter discarded chain are the orphan blocks—they are also called stale blocks.

In 2020, Pieter Wuille, a long-time Bitcoin developer and participant, called these blocks "extinct blocks" because they are no longer active in the blockchain.

How Are Orphan Blocks Differ🎉ent From Uncle Block💟s?

Orphan blocks were common on proof-of-work blockchains and can 𒉰still occasionally occur. Uncle blocks were similar to orphan blocks on the Ethereum blo🅰ckchain when it used proof-of-work. These blocks were mined at the same time as other blocks but were not accepted on the main chain.

Bitcoin and similar blockchains did not reward miners who proposed orph𒈔an b🍌locks, but Ethereum rewarded uncle block producers.

Ethereum transitioned to proof-of-stake in 2022, effectively eliminating uncle block production because the block-producing mechanism is not competitive like Bitcoin's.

The Bottom Line

The definition of an orp🐬han block h🦋as changed as blockchains have evolved. At one time, orphan blocks were blocks that were missing the headers of their parent blocks, but now, they are the blocks in short chains that are rejected by the network because another chain has more proof. They are also called stale blocks.

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