In Corda transaction data is not globally broadcast. Instead it is transmitted to the relevant parties only when they need to see it. Moreover even quite simple use cases – like sending cash – may involve a multi-step negotiation between counterparties and the involvement of a third party such as a notary. Additional information that isn’t put into the ledger is considered essential, as opposed to nice-to-have. Thus unlike traditional block chain systems in which the primary form of communication is global broadcast, in Corda all communication takes the form of small multi-party sub-protocols called flows