A blockchain is a record system of every financial transaction ever made that is kept public, and no one person or institution runs nor owns it. Because this system of a blockchain is uneraseable, uneditable, and can not be tampered with, corrupt crimes of our current traditional banking fiat system such as money laundrying, double spending, and criminals creating counterfeit money can be stopped.

Each coin has its our blockchain, or record book, that is run by a node (a data system), and the data is pumped out by miners, who are processing your transactions for a little miniscule fee, that nowhere compares to the traditional banking fees of today.
The blockchain is not governed by any authority and therefore shows truth.