Consensus Protocol:- Proof of Work (POW)

Blockchain validation is simply the process of finding the block hash. In a blockchain, all the blocks are added to the blockchain after validation only.

Whenever a transaction takes place in the blockchain it will be added to a block; sometimes one transaction per block and sometimes several transactions per block. It depends on the block size and the nature of the

network. When a transaction is added to the block, it must undergo a validation process before it is being added to the blockchain as a valid block. The hash value for the block can be calculated using some algorithms (like sha 256).

In PoW, the mining challenge is open to all. All the miners compete each

other to add the next block. A fixed reward is given to the miner who finds the

solution first. In fact, the node with more computational power usually wins the race. Bitcoin uses the PoW algorithm.

This type of consensus mechanism relies on proof that enough computational resources have been spent before proposing a value for acceptance by the network. This is used in bitcoin and other cryptocurrencies.

Currently, this is the only algorithm that has proven astonishingly successful against Sybil attacks.

But they have one major disadvantage if they valid/verify any transaction to add in block they consume more power ( Electricity power ).

And In future, Bitcoin reward system goes down they effect the 51% attacker they can be prone in future.