drive space. The validators who have more hard drive space for them

have the chance of getting selected for mining the next block and

earning the block reward increases.

Proof of Elapsed Time (PoET)

Widely used in permissioned blockchain networks, PoET is one of the

fairest consensus algorithms which chooses the next block using fair

means only. To create their own block, every validator on the network

gets a fair chance in this algorithm. Adding proof of their wait in the

block is done by all the nodes waiting for a random amount of time.

For the consideration of others, the blocks so created are broadcasted

to the network. The winner is the validator having the least timer value

in the proof part. The block from the winning validator node gets

appended to the blockchain. There are additional checks in the

algorithm to stop the nodes from always winning the election, i.e.,

stop nodes from generating the lowest timer value.

Proof-of-Activity (PoA)

For Bitcoin miners, PoA was invented as an alternative incentive

structure that combines the features of both PoW and PoS. The miners

start with a PoW approach to solve the puzzle in PoA. The system

switches to PoS if the blocks mined do not contain any transactions. A

group of validators is assigned to sign the new block based on the

header information. If a validator owns more coins, he has the highest

chance to be chosen. The template becomes a block as soon as all the

selected validators sign. A new group of validators is chosen if the

validators fail to complete the block, and this process goes on until a

block receives the correct amount of signatures. Between the miner

and the validators, the rewards are divided. Like PoW and PoS, too

much energy is required by PoA. For validation right now, Decred is

the only coin using Proof-of-Activity.

Other consensus algorithms also exist, such as proof of weight, proof

of importance, leased proof of stake, and so on. As the blockchain

network cannot function properly without the consensus algorithms,

you need to wisely choose one as per the business network

requirement to verify each and every transaction being committed.