ZCash is the first blockchain system that uses a zero-knowledge proof mechanism which provides full payment confidentiality while still maintaining a decentralized network through a public block chain. Like Bitcoin, the total amount of Zcash (ZEC) is also 21 million. The difference is that ZCash transactions can hide the senders, receivers and amounts of all transactions on the blockchain. Only those who have the view key can see the contents of the transaction. Users have power of control and they have the option to provide others with a view key.