Relay Nodes

Relay nodes are computers in a peer-to-peer network whose main job is to receive data, such as new transactions and blocks, and forward it to other nodes. In most blockchains every full node relays data as part of normal operation, checking it first so that invalid transactions are dropped instead of spread. Some networks and companies also run dedicated relay networks: fast links between well-connected nodes that cut the time it takes a new block to reach miners worldwide. Faster propagation matters because slow delivery raises the chance of competing blocks and gives an edge to large, well-connected miners. Pending transactions wait in each node's mempool while they are relayed. The term is also used in other designs, such as the relay nodes that pass messages in privacy networks, and should not be confused with Polkadot's relay chain.