If we look at history, a centralized money system has been attacked (physically or digitally), duplicate fake notes have had been made. The transaction charges and time increases as the amount of money we need to send or receive increases. Crypto-Currencies are based on decentralized system of management. People transfer money directly to the concerned person without any middle-man, saving a lots of transaction fees. We can transfer funds worldwide in few minutes. Also the transaction takes place within 6 mins (for bitcoin). Bitcoin is the first global (Digital) currency of Earth as one.