A block chain is a decentralized, distributed and public digital ledger that is used to record transactions across many computers so that the record cannot be altered retroactively without the alteration of all subsequent blocks and the collusion of the network. This allows the participants to verify and audit transactions inexpensively.A block chain database is managed autonomously using a peer-to-peer network and a distributed time stamping server. They are authenticated by mass collaboration powered by collective self-interests.The result is a robust workflow where participants' uncertainty regarding data security is marginal. The use of a block chain removes the characteristic of infinite reproducibility from a digital asset. It confirms that each unit of value was transferred only once, solving the long-standing problem of double spending. Block chains have been described as a value-exchange protocol.This block chain-based exchange of value can be completed more quickly, more safely and more cheaply than with traditional systems.A block chain can assign title rights because it provides a record that compels offer and acceptance.

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