[Blockchain, Decentralization, Block Explorer] - Steemit Crypto Academy Season 5 - Homework Post for Task 4

Write the definition of blockchain.How is our data on the Blockchain protected from hackers? Write details about Data, Hash and Previous Hash tag and explain via screenshot.

Write the definition of blockchain

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For a long time, trust in transactions was provided by individuals, intermediaries or financial entities, it was certainly not possible to know, and it was generally impossible to know who the other party interested in the transaction was, for that reason, we were obliged to use the services of third parties.

In 2008, the world financial system collapsed, taking advantage of these moments of uncertainty, a person named or pseudonym Satoshi Nakamoto, proposed a protocol, creating a new direct electronic payment system between the parties, using a cryptocurrency called Bitcoin, by using of a new technology called Blockchain, a third party was not necessary.

The first Blockchain was created together with the first cryptocurrency, that is, with Bitcoin, all cryptocurrencies to function requires the use of a Blockchain, because it requires that operations be transmitted through an information network and stored in the blockchain.

We can define a Blockchain as a network of distributed information, that is, it works as an accounting ledger that stores the records chronologically, it is said that it is distributed because several copies of the updated information are replicated, they are found in different nodes, that is, in different computers, Blockchain is a compound word, which in Spanish means Blockchain.

How is our data on the Blockchain protected from hackers

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Assuming that a Blockchain is a distributed ledger that is completely open to anyone, the possibility that someone may try to alter a block of the blockchain does not escape.

The mere fact that a blockchain is a distributed network gives it a certain degree of security, since the block chain is replicated to all the nodes that make up the network, this means that each of the nodes that make up the network, which can Thousands and even millions receive an exact copy with the last movement that has been made, to accept a next transaction or block, first the information contained in the block chain in each node is verified, until that moment and all nodes through a system consensus approve or disapprove, if it is approved, then this is when this transaction or block becomes part of the block chain and it can no longer be modified and less eliminated.

The Blockchain adds security, through the use of cryptography, when a block is added to the block chain a code is added that identifies it unequivocally, this code is known as Hash, which is a kind of fingerprint, this hash It is generated through the use of a mathematical algorithm, this algorithm, in order to generate the hash, requires several arguments such as: the transaction data, the hash of the previous block and the answer to an unknown, this answer is achieved through the process called mining or proof of work.

Blockchains also have a mechanism called proof of work, which reinterprets the creation of new blocks, in the case of Bitcoin it takes 10 minutes to calculate the required proof of work and add a new block to the chain, this mechanism does very difficult for them to alter the blocks, because if they alter a block they would have to calculate the proof of work for all the following blocks.

Write details about Data, Hash and Previous Hash tag and explain via screenshot

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Each block contains: Data, Block Hash and Hash of the previous block

• Data:

The data that a block stores depends on the type of Blockchain, for example the Bitcoin block chain stores the details about a transaction, such as the issuer, the receiver and the amount of coins.

• Hash:

The hash can be compared with the fingerprint, it identifies a block and all its content, it is unique, once a block is created its hash is calculated, if altering something inside the block its hash also changes, with the use from the hash we can know if a block was altered

• Hash of the previous block:

It is the Hash that makes a block chain safe, if you alter a block, that makes the hash change, this action makes the next block invalid and all those that follow.

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In the above screenshot I have selected the block 1450 and you can see the the previous hash, hash and data clearly.

This is the end of the Task 4. Thank you for reading my post.