A blockchain is a distributed, public ledger, recording transaction and tracking assets, and of which immutability is guaranteed by a peer-to-peer network of computers, not by any centralized authority. Assets can be tangible, such as homes or cash, or they can be intangible, such as patents or copyrights. A blockchain consists of ordered records arranged in a block structure. Each data block contains a hash (digital fingerprint or unique identifier), timestamped batches of recent transactions, and a hash of the previous block . With this design, each block is connected in chronological order and the connected blocks are called a blockchain. It is practically impossible to modify one of the blocks in the middle of the chain because all of the blocks after the modified block must be modified at the same time. With this mechanism, the data on the blockchain network are immutable.