The most salient feature of a blockchain is its way of decentralizing the power for decision across machines. According to the algorithm of decision-by-majority, the machines build a block containing transactions and chain it to the previous ones after verifying its validity. The chained blocks are then distributed across machines. As long as more than half of machines are operating and functioning properly, the chained blocks are then hardly modifiable because the machines are able to recover the errors through their correct blocks. By doing so, this decentralization algorithm allows verification of transactions, for which the current institutions have been centralizing the power of decision-making to a trusted third party.