A chat server is a computer system that enables real-time communication between users over the internet. It manages messages sent between clients, allowing them to exchange text, images, and other media. Chat servers are commonly used in applications like WhatsApp, Slack, and Discord. These servers operate using various protocols, such as WebSocket or XMPP, to ensure efficient data transfer. They can support multiple users simultaneously, making it easy for groups to communicate. Chat servers can be hosted on dedicated hardware or in the cloud, providing flexibility and scalability for different user needs.