This is a useful lecture.

In the real world, every currency is being priced by how much each country (real community) have of gold/petro in their pocket. So i didn't get how the cryptocurrency works based on the "use" instead of based on the"authenticity". In the real world, the gold-saving/petro amount plays the essential role in validating the currency "authenticity". However, how can cryptocurrency goes up & down without comparing their prices with gold-saving or petro with each dealer/validator (as a member of virtual community) ??!!! How does the "use" give a value to the currency based on believe or choice ? still no answer. or maybe i understood it in wrong way ! still too much ambiguity !