6. Incentive
By convention, the first transaction in a block is a special transaction that starts a new coin owned by the creator of the block. This adds an incentive for nodes to support the network, and provides a way to initially distribute coins into circulation, since there is no central authority to issue them. The steady addition of a constant of amount of new coins is analogous to gold miners expending resources to add gold to circulation. In our case, it is CPU time and electricity that is expended.
6.激励
按照规定，某一个区块上的首笔交易就是创设了一个新币的特殊交易，这个币属于该区块创设者所有。这样为节点支撑网络增添了一种激励手段，因为没有中央集权机构进行发币活动，这样做也同时提供了一种让新产生的币进入流通领域的渠道。稳定增加一定数量新币的机制，类似于金矿矿工花费资源挖矿产生新的能进入流通领域的金子。只不过比特币消耗资源的是电力和CPU的计算时间。
The incentive can also be funded with transaction fees. If the output value of a transaction is less than its input value, the difference is a transaction fee that is added to the incentive value of the block containing the transaction. Once a predetermined number of coins have entered circulation, the incentive can transition entirely to transaction fees and be completely inflation free.
交易费补偿提供了另外一种激励机制。如果一笔交易的输出值小于它的输入值，那么之间的差额就会作为手续费，用来奖励节点把该交易易打包进此区块的（此处参考笑来老师翻译，我的原翻译是：并会进入包含此交易的区块中的激励“奖金池”）。一旦规定数量的比特币已经进入了流通领域，奖励就能全部来源于交易费用，也就完全不受通货膨胀影响。
The incentive may help encourage nodes to stay honest. If a greedy attacker is able to assemble more CPU power than all the honest nodes, he would have to choose between using it to defraud people by stealing back his payments, or using it to generate new coins. He ought to find it more profitable to play by the rules, such rules that favour him with more new coins than everyone else combined, than to undermine the system and the validity of his own wealth.
激励机制也能鼓励节点保持诚信。如果有某个贪婪的攻击者能够聚集起比所有诚信节点更多的CPU算力，他要么会用这些算力去欺诈他人把他已经支付出去的币又偷回来，要么用于产生新币。他应该会发现，依据规则行事更容易带来更大的收益，因为规则能让他们获得的币比其他人所有人加起来都多，能让他获得比破坏这个系统的同时减损自己财富的有效性更多的财富。
7. Reclaiming Disk Space
Once the latest transaction in a coin is buried under enough blocks, the spent transactions before it can be discarded to save disk space. To facilitate this without breaking the block's hash, transactions are hashed in a Merkle Tree [7][2][5], with only the root included in the block's hash. Old blocks can then be compacted by stubbing off branches of the tree. The interior hashes do not need to be stored.
7.磁盘空间回收
一旦一个币中的某个最新交易发生在足够多的区块之前（此处参考笑来老师翻译，我的原翻译是：被所足够数量的区块所证明），在它之前的这个币的花出去的记录都可以被丢弃，以节省磁盘空间。为了能更方便的做到这些的同时不破坏区块的哈希过程，所有交易的哈希都被纳入哈希树，但只有根部部分才会被纳入一个区块的哈希。之前的区块可以通过砍掉哈希树分支的方式进行压缩。区块内部的哈希值无需储存。
A block header with no transactions would be about 80 bytes. If we suppose blocks are generated every 10 minutes, 80 bytes * 6 * 24 * 365 = 4.2MB per year. With computer systems typically selling with 2GB of RAM as of 2008, and Moore's Law predicting current growth of 1.2GB per year, storage should not be a problem even if the block headers must be kept in memory.
一个不包含任何交易信息的区块的头部的大小大约是80字节。我们假设每十分钟产生一个区块，那么一年产生的区块的大小是80字节乘以6乘以24乘以365=4.2MB。2008年市售的一般电脑的操作系统标配2GB的RAM，并且根据摩尔定律，RAM的增长速率是1.2GB每年，所以，即使全部的区块头部信息都保存在内存当中也没有问题。
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