Digital currency was developed by three professors of Stanford University in the United States. At this stage, the test is conducted and it is not on the main network. That is to say, it is centralized now, and there is no decentralization. Centralized hosts and servers are distributed in the United States, Singapore and other countries. Because the China government suppressed digital currency, its international firewall was disconnected, and domestic users could not log on to the pi platform normally. Foreign users can access the pi network normally.