Few days ago a friend asked me this questions. But i cannot understanding that how to i give him answer. At last i said him that, bitcoin is an online currency. Only this currency used in online marketplaces. It is not possible to use it in offline marketplace like offline currency.
But what is your best answer of this question?
Bitcoin is a free currency, and no one is in charge of you, but there is no one to protect you, and everyone needs to arm themselves by studying the principles of bitcoin.
Bitcoin is a kind of network currency, which needs the support of the network to run normally.