In simple terms, public blockchains can receive and send transactions from anybody in the world. They can also be audited by anybody, and every node has as much transmission power as any other. Before a transaction is considered valid, it must be authorized by each of its constituent nodes via the chain’s consensus process. As long as each node abides by the specific stipulations of the protocol, their transactions can be validated, and thus add to the chain
NPD said the next step for retailers is to develop their own cryptocurrency to prevent customers from having to use credit cards when shopping online. NPD said the practice makes sense for the retailer, because if the customer could send the payment transfer via blockchain, it would avoid third-party clearing house fees retailers pay for processing card payments.
A private blockchain network requires an invitation and must be validated by either the network starter or by a set of rules put in place by the network starter. Businesses who set up a private blockchain, will generally set up a permissioned network. This places restrictions on who is allowed to participate in the network, and only in certain transactions. Participants need to obtain an invitation or permission to join. The access control mechanism could vary: existing participants could decide future entrants; a regulatory authority could issue licenses for participation; or a consortium could make the decisions instead. Once an entity has joined the network, it will play a role in maintaining the blockchain in a decentralized manner.