Hello professor @stream4u. I have read your lecture and now I am doing the post. ___ ###

Question 3: What Is Public Chain and What will be the Advantages and Disadvantages of Public Chain?

____ ### Public chain ___ In reality, there are many types of Blockchains technology availabld which are suited for using in different use cases. The examples of some blockchains are private chain, public chains and also federated chains. In this question, I will discuss about Public chains in detail. There are no restrictions in the public chain. The public chain is the type of blockchain which can assessed by anyone with an internet connection and can start validation of blocks and sending transactions. Satoshi nakamoto had suggested this model in the back 2009. This model can also can called as the mother technology. Later, there were interest starting showing by the enterprise companies in the blockchain technology and it tweaked the nature of Decentralized ledger and also introduced another type of blockchain i.e. private chains. The public chain is a decentralized peer to peer network which gives privileges equal to all or any nodes or participants. The network of public chains tends to use the POW (Proof-of-work) or POS (Proof-of-Stake) consensus algorithm for the validation of transactions. Hence, the public chain is completely decentralized and no single entity can control the ecosystem of this unlike the private blockchain which can be changed by the Owning organization. It is also noticeable that the information which is on general public chain has read, but the blockchain can not be modified once and considering this factor, the active participants or nodes and the decentralized networking system are also safe. So it is not possible for hackers to access it. ____ **ADVANTAGES OF PUBLIC CHAINS**: ____ 1. ***Transparency***: It is a fact that the holders of account ensures a highly public transparency in the market and we know that there is nothing more than the transparency in any platform and this proves that there is no manipulation or corruption. 2. ***Total decentralization***: Someone gets the total decentralization with the common public chain in which there is no central person or no central unit. The network is fully decentralized and so all the nodes will have their own copy of ledger. 3. ***Immutability***: This network is immutable completely which means that there is no one who can tamper with system or steal the money. If someone tries to do double spending like scams with the blocks, then other nodes will not allow the transaction and rejects it. 4. Anyone person who has an access to internet connection can download the copy of blockchain and he/she has complete authority to rewrite it. ____ **DISADVANTAGES OF PUBLIC CHAINS**: ____ 1. ***Consensus Mechanism***: The POW consensus mechanism is used by some public blockchains like bitcoin where a mathematically complex problem is need to solve by the participants if they want to validate the transaction and this requires the consumption of many resources which is very costly. 2. ***Speed:*** The speed is one of the major problems with bitcoin like public blockchains in which only 4.6 transactions in a second is processed which is slwo in comparison to other companies like Visa which process 1700 transactions in a second. 3. There is no need to prove the identity by any person in public blockchains and there is just need to commit the processing power to become a part of network. 4. The last negative side of the general public chains is ambiguity. It is because, the malicious people will hide behind the public chains in order to try extra legal activities. ____ ### CONCLUSION ___ The public chain can be accessed by any person with an internet connection and there are no restrictions. Any person can start doing validation of blocks and can send transactions and this uses the POW and POS consensus algorithm for the validation of transactions.