Bitcoin has changed the world's currency system. The technology that has made the biggest impact in the past few decades. It is not the mass media. Nor is the global data block. Not a robot. Not even artificial intelligence. You will be surprised to find out that this is the basic technology of the Bitcoin digital currency system. That system is called blockchain. It is not a fashionable word in the world, but I believe it is the next generation of internet, and it is promising for every economy, every society and for all of you, one by one.