By approving a transaction with their private key, the user directs the wallet application to broadcast the transaction via a remote procedure call (RPC) node. An RPC node is a server or computer that receives the signed transaction data from the user and then propagates it across the blockchain network so it can be validated by other nodes and eventually included in a block. There are many RPC nodes run by individuals and groups around the world, contributing to the decentralized nature of blockchain networks.