I think bitcoin is a world currency not a private currency and because he does not hold by the government and does not have tax.. and i am agreed for this currency. so all people are wrong tell us bitcoin is a private currency.
I have not even heard of anyone claiming that bitcoin is a private currency. In a purely legal sense, such an assertion would be incorrect, because bitcoin does not belong to any private person. With such an expression, one can agree that bitcoin will be used primarily by private individuals. States or government agencies are unlikely to make extensive use of bitcoin.
Not every country are accepting Bitcoin as a legal digital currency but it is not a private currency. A private currency can be owned by any private or non-private organizations, on such details Bitcoin doesn't fit in to this status as Satoshi didn't own it but he releases it as a public digital currency with the help of blockchain, all the transactions are being recorded and can be viewed publicly.