Bitcoin is a peer-to-peer electronic cash system, more directly, node-to-node. Each transaction is broadcast to the surrounding nodes by the initiating party. After receiving the broadcast, the node broadcasts it to the surrounding nodes, and eventually spreads to the entire network.
Every Bitcoin wallet is a node, and the node with the complete blockchain ledger is called a full node. In October 2017, there were approximately 9,300 full nodes on the Bitcoin network, responsible for broadcasting and verifying Bitcoin transfer transactions.
After the transfer transaction occurs, it is broadcasted by all nodes to the entire network. The mining node verifies that the transaction is correct and records it in the blockchain ledger.
The United States, Germany, and France have the largest number of Bitcoin full nodes, and the number of full nodes in China accounts for about 5% of the world (data source: bitnodes.21.co). Running Bitcoin nodes does not provide any rewards, and Bitcoin transfer can be performed without a full node, so the total number of Bitcoin full nodes only accounts for a small portion of the total number of nodes.
