Figure 5 .6 : An uncle block

(Source: medium.com/ @

vrastromind/ the-forked-uncle-block-in -the-ethereum-9ca8b0447796)

An uncle block gets rej ected from the main blockchain, due to its working

mechanism, in spite of it being mined genuinely and being valid.

A blockchain is formed by blocks that store details of transactions taking

place on the network where the miners follow the standard mining process

to mine for the new blocks. After the verification process and the addition

of the newly found block to the blockchain, which increases the length of

the blockchain called the block height, the miner finding the new block is

entitled to the block reward. Two different miners at times may generate a

block simultaneously, which happens on account of the working mechanism

of blockchain that instantaneously does not accept the newly identified

block into the blockchain. The resulting delay leads to a situation in which

some other miner solves for the same exact block and is now trying to add it

to the network chain that results in a dubious state of the network,

temporary in nature, as the various nodes are trying to build a consensus on

the newly identified block to continue with, and the one which is to be

rej ected.

A block with a larger share of proof of work j oins the blockchain working

as a normal block, and the one with a lower share, which includes the uncle

block, is rej ected.

The concept of a family tree is considered as a blockchain with accepted

blocks having a parent-child relationship in the tree; the word “uncle” is

based on these lines. Though the uncle is close to the parent, he is not a part

of the nuclear family and hence related but separate from the family, i.e.,

the blockchain.

Ethereum provides incentives to uncle block miners, whereas the Bitcoin

network does not reward orphan blocks. As valid uncle blocks are

rewarded, which helps in decreasing the decentralization of incentives in

the case where large mining pools with high computing power claim the

maj ority of rewards, leaving nothing for the individual miners, the effect of

network lag on the distribution of mining rewards is neutralized. The

security of the network increases by supplementing the work on the main

blockchain with the work done in mining uncle blocks.

Block timing