A server node is a single server that is part of a larger network or system, often used in cloud computing or data centers. Each node can perform tasks independently, such as processing data or hosting applications, and they work together to provide services more efficiently. In a distributed system, multiple server nodes collaborate to handle requests and share resources. This setup enhances reliability and scalability, as the workload can be balanced across different nodes, reducing the risk of downtime and improving performance for users accessing services like web applications or databases.