What is the difference between PoW & PoS? Advantages & Disadvantages? Which one is better in scaling Capacity? Examples?

Hello my dear steemians,how are you all ,i hope you all are fine.Today i am here to post my task 4 ,that was made available to us by professor @sapwood and i am very thankful to him as he has used a valid effort to make us understand the lecture.

CONSENSUS MECHANISM

Let me first discuss concensus mechanism.
A consensus mechanism as the name indicates is the process through which nodes in a blockchain reach a concensus while dealing with a transaction ,validates it and gives the newly added blocks a proper order and security.Two main consensus mechanisms are Proof of Work (PoW) and Proof of Stake (PoS).

What is Proof of Work (PoW)

The concept of“proof of work” was first given by Cynthia Dwork and Moni Naor and the term was coined by Markus Jakobson and Ari Juels in 1999. It is also the first mechanism that was used in case of blockchain networks .Proof of Work (PoW) is a decentralized protocol designed to validate digital transactions and make them secure. It is the most widely used mechanism. It is based on the principle of puzzle solutions where miners use computer hardwares called Mining Rigs containing( Graphics Processing Units and ASICS) which algorithmically solve complex mathematical puzzles.These mining rigs consume a lot of electrical energy while in operation.This work of solving the mathematical puzzle is called mining.The miner who solves the puzzle first broadcasts the new block to all other nodes, which inturn verify the block and add it to their record and agree with each other in recognizing the data and hence reach a consensus. Mining generates rewards for the workers and these rewards are called block rewards e.g bitcoins in case of bitcoin blockchains.Solving the algorithms helps in substantiating the transaction and adding new blocks to the blockhain.In Proof of Work, every miner strives to be the first to finish a complex mathematical puzzle and add a new block to the blockchain and obtain the rewards.
PoW does not allow miners to add infinite blocks to the network by setting a time limit of 10 minutes i.e miners can add a new block to the network only after 10 minutes.PoW proves to be a challenge before the hackers because of certain reasons and the main reasons being

• Same data related to a transaction recorded on all the nodes and a tough task to temper data on 51% of the blocks.which will increase the cost as expensive resources are required to temper the data and as such the cost required to hack will be greater than the achievement.

2. What is Proof of Stake (PoS) ?

To overcome the shortcomings of PoW,a new consensus mechanism was invented and given the name PoW (Proof-of-stake).As PoW involves miners ,PoS involves validators ,a validator is a person or we may say validators are network node operators who has put some coins or the native tokens of that particular blockchain on stake and based on the number of coins /native tokens on stake this consesus mechanism determines who validates a block,i.e the person with more number of coins on stake will get an assignment of validating a transaction at that particular instant.In case of PoW ,miners have to work on puzzle solving which requires an expensive hardware and huge amount of electricity,PoS does not need such hardware and that much electricity .This system randomly selects a validator to validate a transaction block based on how many coins /tokens that validator has staked.More chances to validate a transaction block for a validator who has more coins /tokens on stake. And that particular validator is rewarded with some transaction fees after the block is confirmed.As the validator is rewarded after the actual confirmation of that block ,the validator is bound to provide honest data and do his work honestly otherwise he may loose his stake and also the transaction fees through a mechanism called 'SLASHING'.This ensures the security of the network as hackers would need to own 51% of all cryptocurrency on the blockchain network, which is practically impossible.

Summary of differences between two consensus mechanisms .

S.No	Proof of Work (PoW)	Proof of Stake (PoS)
1.	Validating a transaction data is based on mining i.e mathematical puzzle solving and the person who solves the puzzle first gets the reward	Selection of a validator to validate a transaction data is based on how many coins a person has on stake i.e more number of coins on stake more are the chances to get a chance to validate a transaction.
2.	In PoW ,rewards in the form of cryptocurrency are recieved to validate a block.	In case of PoS ,transaction fee is recieved by a validator.
3.	Here miners compete with each other to solve mathematical puzzle as early as possible and validate a block to earn the rewards.	Here validators do not need to compete as the validator with more in stake will be chosen to validate a block and earn the transaction fees.
4.	Here investmment is needed to buy hardware.	Here investment is needed to buy coins/tokens to stake.
5.	Proof of work systems require a huge amount of energy to operate and are thus less efficient and are also are a reason to global warming because mostly the energy requirements are fulfilled by using fossil fuels	Proof of Stake systems require less energy to operate and are thus energy efficient.
6.	In PoW,validation can only be done by a professional as it requires a lot of knowledge and skill related to the field of cryptocurrencies.	In PoS ,validation can be done by anyone ,it does not require any skill or knowledge but only requires coins in the wallet .
7.	Here transactions are slow because of puzzle solving that takes some time.	Here the transactions are fast as no puzzles are solved.
8.	It has low scalability capacity(capacity to process transactions).	It has high scalability capacity.
9.	Example: Bitcoin Litecoin	Example: Cardano(ADA), EOS(EOS).

2). Advantages & Disadvantages of Proof-of-Work (poW) and Proof-of-Stake (PoS)

Advantages and disadvantages of Proof-of-Work.

Advantages	Disadvantages
It provides equal chances to miners and the miner who is able to solve the puzzle earlier as compared to others gets the reward	A lot of effort ,energy and computation costs are involved because of many miners working on the same puzzle and only one is able to recieve the reward.It also provides barriers to entry because of its high initial cost.
The system is fully decentralized and no one has the command which makes it transparent and free to work with.	A lot of costly hardware and electricity is required to operate.As a large portion of the electicity required in present day world is generated from fossil fuels ,more energy consumption means more usage of fossil fuels which adds green house gases to the environment and thus increase global warming.
Rewards provided to a miner are more as compared to transaction fee provided by PoS to a validator.	51%malicious miners could dominate the network and can thus result in a failure,which is also termed as 51% attack.

Advantages and disadvantages of Proof-of-Stake

Advantages	Disadvantages
It does not require high initial cost i.e it does not require costly hardwares and high electricity for its operations and provides less barriers to enter the network.	It is mechanism which favors the rich i.e a validator with more coins in stake will be favored and thus this mechanism discrimates the validators on the basis of how much they stake.
It takes less time for a transaction as it does not require to solve complex mathematical puzzles .	Persons with less amount to stake or the validators with less number of coins to stake may not be able to take part in the validation.

Which one is better in scaling Capacity? Examples?

Scaling capacity or scalability is the ability of a blockchain network to continue to function properly while changes are being made in its block size.Processing of a transaction in a blockchain depends upon the block size of that network .A block with less size e.g 1mb block will take more time to process transactions as compared to a 10mb block .As a transaction is processed and validated in a network and then recorded on a block ,the process requires to be finished first and only after then next transaction is processed.So a network with more block size is able to process a transaction in less time and has thus more scaling capacity .In case of PoW and PoS ,PoS has more scaling capacity and is faster than PoW.

Examples of networks that use PoW mechanism are

Bitcoin
Litecoin
Ethereum

Examples of networks that use PoS mechanism are

Peercoin (peercoin was first to use PoS mechanism)
Cardano
Binance
Polkadot.

I hope i am clear to my professors and curators.
Thank you very much.