How does Blockchain works?

Hello Steemitians,
We all are hearing the news about Blockchain and different Cryptos. But what is a Blockchain? How do they work? What problems do they solve? And how can they be used?

Blockchain are incredibly popular nowadays. Like the name indicates, a Blockchian is a chain of block's that contains information. This technique was originally described in 1991 by a group of researchers and was originally intended to timestamps digital documents so it's not possible to back to them or to tamper with them. However it remains mostly unused until it is used by Satoshi Nakamoto in 2009 to create digital cryptocurrency, Bitcoin.

Blockchain is distributed ledgers that are completely open to anyone. They have an interesting property .Once some data has been recorded inside Blockchain; it becomes very difficult to change it.
So how does that work?

Well let’s look the close look at a block. Each block consumes some data, the Hash of the Block and hash of the previous block. The data that is stored inside a block depends on type of Blockchain. The Bitcoin Blockchain for example, stores the details about transaction in year such as the sender, receiver and the amount of points. A block also has a Hash . You can compare hash to your fingerprints. It identifies a block and all of its contents and it's always unique just as a fingerprint. Once the block is created, its hash is being calculated. Changing something inside the block will cause the hash to change. So in other words hash is a very useful when you want to detect changes to blocks. If the fingerprints of block changes, it’s no longer a same block.
The third elements inside each Block is the hash of the previews block .This effectively creates the chain of blocks this technique makes Blockchain so Secure. But using hashes is not enough to prevent tempering. Computers these days are very fast and can calculate hundreds of thousands of hash per second you could effectively temper with block and recalculate all the hashes of other blocks to make your Blockchain valid again.

So to solve this, Blockchain have something that is called proof of work. It's a mechanism that slows down the creation of new blocks. In Bitcoin case, it takes about ten minutes to calculate to require proof of work and adding new block to chain. This mechanism makes it very hard to tamper with the blocks because if you tamper with one block, you need to re-calculate prove of work for all the following blocks. So the security of a Blockchain comes from its creative use of hashing and Proof of work mechanism.
Moreover, the distributed ledger technology uses Peer-Peer (P2P) network and everyone is allowed to join .When someone joins this network he gets a fool copy of Blockchain and it can be used to verify that everything is still in.

Creation of Blockchain technology have pick a lot of people interest. Soon other will realize that this technology can be used to store medical records, creating the digital notaries or paying taxes.

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