 blockchain that is structure of a blockchain, myself Rashmi Dixit, so let us begin the session. Learning outcome, at the end of this session students will be able to analyze structure and working of a blockchain. As we have already seen what is blockchain, what are the different properties or what are the different types of a blockchain, we will revise here in a couple of minute. So blockchain it is a decentralized computation and information sharing platform that enables multiple authoritative domains who do not trust to each other to cooperate, coordinate and collaborate in a rational decision making process. In a traditional worldwide web, a client server architecture is used in which a data or information is stored at one place which is managed or controlled by a single entity that is a server. On the other hand, in a distributed blockchain a data is stored at multiple nodes or stored at a multiple participant within a network which maintain, approve and update new entries. So blockchain is a decentralized working environment. So what is the difference in blockchain and traditional database? So in blockchain only insert operation is possible while as we have all of you know that we can perform crude operations in a traditional database. In blockchain a full replication of block on every peer is possible while in traditional database master slaw multi master replication is possible. Majority of peers who are working in that particular environment agree on the outcome of transactions in blockchain in traditional database two PC or two phase commit protocol is used to check the working in a distributed environment. Anybody can validate transactions across the network that is the main point. Every network peer has a authority to validate the transactions. Anybody can validate transactions across the network in traditional database there are some integrity constraint. So let us see what are the core components of a blockchain. So node user or a computer within the blockchain transaction smallest building block of a blockchain system block a data structure used for keeping a set of transactions which is distributed to all nodes in the network chain a sequence of blocks in a specific order minors specific nodes which perform the block verification process concerns a set of rules and agreement to carry out blockchain operations. Let us look here the simplified blockchain. So every node maintain a public copy of global data sheet but before that blockchain consist of number of nodes which are connected to each other. So number of nodes now one thing that node may belongs to different organization that is important. Each node has a local copy of the ledger as well as public copy of the global data sheet. The system ensures consistency among the local copies the system ensures the local copies at each node is identical plus the local copies are always updated based on global information. The nodes communicate with each other in order to gain agreement on the content of a ledger. The purpose of gaining the agreement is called as concerns and there are number of different algorithms that have been developed for this purpose. Public ledger important term in case of a blockchain. So what is public ledger a database of historical information which is available to everyone. So that is important public ledger is shared in a distributed environment for each and every node. So blockchain with a number of nodes may belongs to different organization and communicate with each other. So what is the structure of blockchain? It is a data structure that is correct but there are two vital things are used. One is pointer what is a purpose? It is variables that keep information about the location of another variable. It point to the next location and linked list a sequence of blocks where each block has a specific data and link to the following block which with the help of a pointer. So pointers and linked lists. So pointer points to the next block which consists of data again pointer to the next block. So this is a sequence diagram of a blockchain in detail. Each blockchain block consists of certain data the hash of the block and the hash from the previous block. There is a one thing Merkle root. So what is a Merkle root? Every transaction has a hash associated with it. We know that the Merkle root is the hash of all the hashes of all the transactions in the block. The Merkle root is a part of block header that we all have seen in the previous diagram that Merkle root is a part of header etc etc but the Merkle root is also known as hash tree which is a data structure in a cryptographic manner that is important. Leaf node is a hash of block of a data and each non-leaf node is a hash of its child node. The benefit of using Merkle tree in a blockchain is that instead of downloading every transaction and every block a light client can only download the chain of block header. Also if someone's needs to verify the existence of a specific transaction in a block then that particular does not need to download the entire block. Downloading a set of plans of history is enough so no disturbance at all. So how blockchain works in a diagrammatic manner? So user sent a transaction request to a blockchain in order to perform the operation the chain is designed to provide so a transaction is requested. A block that represents a transaction is created that is important. So block that requests the transaction is created that block is sent to every node. Node validates the transactions for which that block is sent to node. So node receiver reward for the proof of the work. After that the block is added to the existing chain and the transaction is complete. So blockchain is a data structure to create and share distributed ledger of transaction among a network of computers. Basically it uses peer to peer network of a computer to validate a transaction. It allows user to make and verify transaction immediately without a central authority. Any new record or transaction within the blockchain implies the building of a new block. Each record is digitally signed. So all of you student please pause the video and try to think and write down the answer for the following question. So blockchain architecture can serve which of the following purpose of the organization. Think for a while and try to write down cost reduction yes history of a data is possible this ledger public ledger consist of database of a history of all transaction data validity and security yes each transaction which is digitally signed or digitally each record is digitally signed. So before conclusion or before reference blockchain is considered incorruptible. The first and in fact the prime difference in blockchain is a digital ledger that can be decentralized very easily. The chances of error in this approach are far less. So these are the references. Thank you.