I. Introduction
Blockchain originated from the idea of Bitcoin. So, it is important to understand what Bitcoin is. The Bitcoin system is based on peer-to-peer network, where transactions carried between users directly, without an intermediary. These transactions are verified by nodes in network and recorded in a public distributed ledger called a Blockchain. Blockchain can be called the spine of the entire crypto-currency system. Blockchain technology makes sure of security and anonymity of the participants involved. Blockchain is also called as an open and distributed or shared ledger, which records transactions between two participants in a verifiable and non-editable manner.