Blockchain is the technology behind the most controversial currency I am talking about bitcoin. The most simple definition of blockchain is that " distributed, decentralized public ledger".
Here we will discuss about blockchain in a little detail and will talk about how does it work.
Blockchain is the cluster of public database computer networks where information is stored. In the term blockchain, the word block means information while chain means public database. In terms of bitcoin blockchain works as a data storage house where the information like transaction date, time and the amount of bitcoins are stored. Blocks store information in a digital form called hash (cryptographic codes) which distinguish them from the other blocks)
and to add blocks in a blockchain there are some protocols which must have to follow like transaction must have occurred, must be verified the block must be given a hash after that the block is added to the network.
The hash rate of each block is in a sequence to its previous block so if someone wants to change the block it must have to change the hash rate of each block which are formed after that and it needs an enormous amount of computing power to change the hash rate of each block and we also know that each public database has a copy of the blockchain and these public databases verify the transactions so its almost impossible to alter the blockchain.