Orphan Block/Uncle Block

Orphan Block/Uncle Block

Orphan Block - This is the block (also called stake blocks) which are not accepted into the blockchain network due to the delay in broadcasting the block the network. Having said that, an Orphan block is created when two miners (or more) find the solution at the same time. While Orphan blocks are still valid and verified (after the proof of work mechanism had been carried away correctly). Since the Orphan blocks are not added to the network/blockchain, they are stored in a pool of orphaned blocks, thus does not have any meaning to the entire network/blockchain. Miners who have successfully generated blocks that become orphan block do not receive any reward. An average of 1 to 3 of all the blocks generated in the network in a day are orphans. The most common blockchains that do not reward orphan blocks are Bitcoin, Bitcoin Cash (BCH), Dogecoin (DOGE), Litecoin (LTC) and ZCash (ZEC); while other blockchains might reward. The following figure will best explain the orphan block

 

 

Image Source: Internet

Now lets say, both the chain contains same number of blocks; and which one would become the orphan chain/block and the other the main chain? Did you think of this? There is a tie? 

 

But this is simple. Out of the two chains (A & B have same number of blocks). Let's say chain A has added the new block faster than chain B. Thus, chain B will be discarded and chain A will be considered the main chain.  

 

Uncle Block - Uncle block is specific to Ethereum blockchain/protocol, where uncle blocks are created when more than one child block is created from a parent block. It’s often said that Uncle blocks are bound to be created many times because all the nodes that maintain the ledger are not updated immediately when a new block is mined. In short, when two blocks are mined simultaneously, only one gets validated across the nodes on the ledger and the one that is left unconfirmed become an uncle block. While miners of an orphan block are not rewarded for producing them, miners are rewarded for producing an uncle block. For a valid block successfully mined on the Ethereum network, a miner is rewarded with a block reward of 3 Ether. Contrarily, a miner of an uncle block earns a reward of 2.625 Ether. What happens to the transactions in orphan blocks? The transactions are not processed on the main chain i.e., if the block containing transaction is orphaned, the transaction gets discarded. The wallet balance of the sender will be the same as it was prior to transferring the funds and the destination wallet will not see any incoming funds.