How does a block chain works?
Blockchain are incredibly popular nowadays. But what is blockchain? How do they work? What problems do they solve and how can they be used like the name indicates, a blockchain is a chain of blocks that contains information. This technique was originally discussed in 1991 by a group of researchers and was intended to timestamp digital documents so that its to backdate them. Or to tamper with them. Almost like a notary. However it went by mostly unused until it was adopted by Satoshi Nakamoto in 2009. To create the digital cryptocurrency bitcoin. A blockchain is distributed ledger that is completely open to anyone. They have an interesting property once some data has been recorded inside a blockchain. It becomes very difficult to change. So how does it work? Well let's a closer at a block. Each block contained some data that is stored inside the blocks depends on the type of a blockchain. The bitcoin blockchain for example the details about a transaction in here such as the sender, the receiver, and the amount of coins. A block also has a hash. You can compare a hash to a fingerprint. An identities a block and all of its contents and is always unique. Just as a fingerprint. Once a block is created, its hash is being calculated. Changing something inside the block will cause the hash to change. So in the other words hashes are very useful. When you want to collect changes to blocks. If a fingerprint of a block changes its no longer is the same block. The third element inside each blocks is the hash of the previous blocks. This effectivity creates a chain of blocks and it's technique that makes a blockchain so secure. Let's take an example. You have a chain of three blocks. As each blocks has a hash and the hash of the previous blocks. So block number 3 points to block number two and number two points to number one. Now the first block is special it cannot point to previous block because its the first one. How let's say that you tamper with the second block. This causes hash if the block two changes as well. The term that will make block three and all the blocks invalid because they no longer store. So changing single blocks will make all following blocks invalid. But using hashes is enough to prevent tampering. Computer these days are very fast and very calculate hundreds of thousands of hashes per second. You could effectively tamper with a block and recalculate all other blocks to make your blockchain valid again. So to mitigate this, blockchain have something called proof of work.. Its mechanism that slows down the creation of new blocks. This mechanism makes it very hard to tamper with the blocks because because if you tamper with one block. You'll need to recalculate the proof of work for all of the following blocks. So security of a blockchain comes from its creative use of hashing and the work of proof works mechanics. Second way is distribution instead of using a central entity to manage the chain.. Blockchain use a peer to peer network and any allowed to join. When someone gets the network the full copy of blockchain. The node can use this to verify that everything is still. In order. When someone creates a new blocks. That blocks is send to everyone network. Each node verifies the block to make sure it has been tampered with. If everything checks out, each node and this blocks to their own blockchain.