The whole point of using a blockchain is to let people, in particular, people who don’t trust one another share valuable data in a secure, tamper-proof way.Blockchain consists of three important concepts: blocks, nodes and miners.A blockchain is a decentralized ledger of all transactions across a peer-to-peer network. Using this technology, participants can confirm transactions without a need for a central clearing authority. Potential applications can include fund transfers, settling trades, voting, and many other issues.this book will explore what blockchain is? and where it is going in 2020?