How does a blockchain work
block chains are incredibly popular now a days but what is the blockchain how do they work what problems do they solve and how can they be used like the name indicates a block chain is a chain of blocks that contains information this technique was originally described in nineteen ninety one by a group of researchers and it was originally intended to time stamp digital documents so that it's not possible to back date them or to tamper with them almost like a nursery however it wasn't by mostly unused until it was adapted by those she neck i'm also in two thousand and nine to create the digital crypto currency bitcoin now a blockchain is a distributed ledger that is completely open to anyone they have an interesting property one some data has been recorded inside of blockchain it becomes very difficult to change it so how does that work well let's take a closer look at a block each block contains some day
the hash of the block and the hash of the previous block the data that is stored inside a block it depends on the type of blockchain the bitcoin blockchain for example stores the details about a transaction in here such as the sender receiver and the amount of coins a blog also has a hash you can compare a hash to a fingerprint it identify size of block and all of it's contents and it's always unique just as a fingerprint once a block is created it's is being calculated changing something inside the block will cause the hashtag change so in other words hashes are very useful when you want to detect changes two blocks it's the fingerprints of a block changes it no longer is the same block the third elements inside each block is the hash of the previous block and this effectively creates the chain of blocks and it's this technique didn't miss
the blockchain so secure let's take an example here we have a chain of three books as you can see each block has hash and the hash of the previous block so block number three points to block number two and number two points to number one now the first block is a bit paschal it cannot point to previous blocks because well it's the first one we call this block the genesis block now let's say that you tamper with the second block this causes the hash of the block to change as well in turn that will make bought three and all falling blocks invalid because they no longer store a valid hash of the previous block so changing a single block will make all following blocks valid but using hashes is not enough to prevent tampering computers these days are very fast and can calculate hundreds of thousands of hashes per second you could affect