Message switching is a network switching technique where the entire data message is routed from the source node to the destination node through intermediate switches. Each intermediate switch stores the full message until there are sufficient resources to forward it to the next node. If the network is congested, messages are stored until capacity is available. Message switching was used before packet switching but has been largely replaced, though it is still used in some networks due to its store-and-forward efficiency. However, it requires significant storage at each node and can be slow.