Blockchains are divided into three categories, which are described in detail in the book blockchain: defining a new pattern of future finance and economy issued by the currency. Hybrid blockchain and private blockchain can be regarded as private chains in a broad sense.

public

Public blockchain (public block chains) means that any individual or group in the world can send a transaction, and the transaction can be effectively confirmed by the blockchain, and anyone can participate in its consensus process. The public blockchain is the earliest blockchain and the most widely used blockchain. The virtual digital currencies of each bitcoin series are based on the public blockchain, and there is only one in the world A blockchain corresponding to this currency.

union

Industry block chains: multiple preselected nodes are designated as bookkeepers within a group. The generation of each block is jointly determined by all preselected nodes (preselected nodes participate in the consensus process). Other access nodes can participate in transactions, but do not care about the bookkeeping process (in essence, it is managed bookkeeping, but it becomes distributed bookkeeping. How many pre selected nodes and how to determine the bookkeeper of each block become the main risk point of the blockchain), anyone else can conduct limited query through the open API of the blockchain.

private

Private block chains: only the general ledger technology of the blockchain is used for bookkeeping. It can be a company or an individual, and the writing permission of the blockchain is exclusive. This chain is not very different from other distributed storage schemes. (dec2015) conservative giant (traditional finance) They all want to experiment with private blockchain, while the application of public chain, such as bitcoin, has been industrialized, and the application products of private chain are still under exploration.