$BTC

One of the main features of the system is complete decentralization: there is no central administrator or any equivalent. The necessary and sufficient element of this payment system is the basic client program (it has open source code). The client programs run on multiple computers connect to each other in a peer-to-peer network, each node of which is equal and self-sufficient. One of the consequences of decentralization is the potential for 'double spending', that is, the transfer of the same bitcoins to different recipients. Under normal conditions, this is protected by the inclusion of a transaction in the blockchain. However, if more than 50% of the total computational power of the Bitcoin network is controlled, there exists a theoretical possibility of 'replacing' one chain of transactions with another.