If you ask me what is the hottest event in 2017 on internet, I would say bitcoin. Its market capitalization has increased by 500% in this year (2017) until now, and still increasing. Blockchain is a technology behind bitcoin, following is the explanation from wiki.
A blockchain – originally block chain – is a continuously growing list of records, called blocks, which are linked and secured using cryptography. Each block typically contains a hash pointer as a link to a previous block, a timestamp and transaction data. By design, blockchains are inherently resistant to modification of the data. A blockchain can serve as "an open, distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way."[not in citation given (See discussion.)] For use as a distributed ledger, a blockchain is typically managed by a peer-to-peer network collectively adhering to a protocol for validating new blocks. Once recorded, the data in any given block cannot be altered retroactively without the alteration of all subsequent blocks, which needs a collusion of the network majority.
-- From wiki
There are hundreds of virtual currency now. You may be confused about the blockchain, bitcoins ethereum, etc. In fact, the technology behind them is similar. Here we collect some books to explain Cryptocurrency, Blockchain, Bitcoin, Ethereum etc. I'm sure blockchain will improve people's lives in some ways. Hope you like these books.