SMPP, or Short Message Peer-to-Peer, is a protocol used for sending and receiving SMS messages between a service provider and an application. It allows for efficient communication and is widely used by businesses to send bulk messages, such as alerts or promotional content, to customers. The protocol supports various features, including message delivery reports and the ability to send messages to multiple recipients. SMPP is commonly utilized by mobile network operators and SMS aggregators, making it a crucial component in the mobile messaging ecosystem.