We know that each transaction is stored in the blockchain, and we can trace back to the details of each transaction based on the blockchain, as shown in the figure below, including the number of inputs, the number of outputs, the public key of the previous transaction hash and the payment object. Public and private key encryption appears here, for each Bitcoin account will generate a pair of keys, public and private keys, public key relative to the address, sent to the Internet to let everyone know that there is such an address. The private key can only be known to the current account. Simply put, if A wants to transfer to B Bitcoin, A encrypts the transaction with its own private key, the destination address is B's public key address, and B receives the transfer, then use A's public key to decrypt the destination address inside to receive the transfer for itself. Such a cycle back and forth. In this way in the network are public key as the address, if you do not tell others in the real world your public key address, you are anonymous, user privacy will not be disclosed.