XMPP, or Extensible Messaging and Presence Protocol, is an open-standard communication protocol used for instant messaging and presence information. It allows users to send messages and check the availability of their contacts in real-time. XMPP is widely used in various applications, including chat services and social networking platforms. One of the key features of XMPP is its extensibility, which means developers can add new functionalities without changing the core protocol. This flexibility has led to its adoption in various fields, from gaming to IoT (Internet of Things), making it a versatile choice for real-time communication.