Virtual currencies however are exchanged on a decentralized peer to peer network.

然而，虚拟货币是在分散的点对点网络上交换的。

This prevents people from spending the same Bitcoin more than once since everyone else on the currency's peer to peer network knows that it just was spent.

这可以防止人们多次消费相同的比特币，因为该货币的点对点网络上的其他人都知道它刚刚被消费了。