区块链的概念和特征都有哪些？

　　区块链技术最早由Inter的高级专家蒂姆梅于1992年提出。区块链是一系列现有成熟技术的有机组合，它对账本进行分布式的有限记录，并且提供完善的脚本以支持不同的业务逻辑。在典型的区块链系统中，数据以区块链(block)为单位产生和存储，并按照时间顺序连城链式(chain)数据结构。所有节点共同参与区块链的数据验证、存储和维护。新区块的创建通常需得到全网多数(数量取决于不同的共识机制)节点的确认，并向各节点广播实现全网同步，之后不能更改或删除。

The block chain technology was first introduced in 1992 by the senior Inter-American expert Timme. The block chain is an organic combination of a range of existing mature technologies, with a limited distributional record of the books and a refined script to support different business logics. In typical block chain systems, data are generated and stored in blocks (block) and linked to a time-series (chain) data structure. All nodes participate in data validation, storage and maintenance of the block chain.

　　由于区块链网络中的所有节点都保存着整个数据库的所有数据，因此区块链的存储容量较小、写入效率也较低。为了平衡区块链的优缺点，出现了面向不同范围用户开放的区块链类型，包括公有链、联盟链和私有链，通过部分“去中心化”，提升区块链的存储写入效率。

Since all nodes in the block chain network hold all data from the entire database, the storage capacity and writing efficiency of the block chain is smaller. To balance the advantages and disadvantages of the block chain, the type of block chain that is open to a range of users has emerged, including the public chain, the union chain and the private chain, increasing the storage efficiency of the block chain through partial “decentralization”.

　　公有链：公有链是对所有人开放，任何人都可以参与的区块链，完全去中心化。公有链不受任何机构控制，账本完全公开透明，任何人都可以参与到区块链的维护和数据读取中来。其共识过程的参与者通过密码学技术以及内建的经济激励维护整个网络数据库的安全。公有链的项目包括比特币、以太坊、瑞波，还有大多数竞争币及智能合约平台。

Public chain: The public chain is open to all and anyone can participate in the block chain, which is completely decentralised. The public chain is not controlled by any institution, the books are completely open and transparent, and anyone can participate in the maintenance of the block chain and in data access. Participants in the consensus process maintain the security of the entire network database through cryptology technology and built-in economic incentives. The public chain projects include Bitcoin, Etheria, Rapo, and most competitive currency and smart contract platforms.

　　联盟链：对特定的组织团体开放，参与区块链的节点是事先选择好的，节点间很可能有很好的网络连接。可以采用非工作量证明的其他共识算法，可以做到很好的节点之间的连接，成本低且交易速度非常快，交易成本大幅降低甚至为零。联盟链中的数据读取权限是分级别的，对外、对内以及内部各节点之间的权限也可以不一样，这就使得数据有了一定的隐私，联盟链是“部分去中心化”的代表。目前国内外大部分区块链项目都是基于联盟链进行开发的，如R3联盟、京东金融ABS云平台、云象区块链等。

Alliances: Open to specific groups of organizations, participation in the nodes of the block chain is pre-selected, and there may well be good network connections between nodes. Other consensus algorithms that are not supported by workload can be used to achieve good connections between nodes, low cost and fast pace of transactions, and transaction costs can be significantly reduced or even zero. Data access in the node is hierarchical and varies between external, internal, and internal nodes, which gives some privacy to the data, which is represented by “partial decentralization”.

　　私有链：对单独的个人或实体开放，参与节点只有自己，数据的访问和使用有严格的权限管理。有人认为这就是传统意义上的共享数据库，如果私有链在实践中不能充分利用公有链所构造的去中心化的信任基础，其发展空间将是非常有限的。

Private chains: are open to individual individuals or entities, participate in nodes only of their own, and access to and use of data is subject to strict delegation of authority. It is suggested that this is a traditional shared database, and that if private chains fail in practice to take full advantage of the decentralized trust base built by public chains, their development space will be very limited.

责任编辑：胡金鹏