server

A server is a computer program or device that provides functionality for other programs, called clients. In a networked environment, a server offers services such as data, resources, or processing power, and handles requests from clients. A server can be a dedicated physical machine or a software process running on a general-purpose computer; many modern deployments use virtualization or cloud infrastructure, allowing multiple server instances to run on shared hardware.

Common server types include web servers, database servers, file servers, mail servers, and application servers. A web server processes HTTP requests and serves static or dynamic content. A database server manages a database engine and responds to query requests. A file server shares files across the network. A mail server handles email transfer, storage, and delivery. An application server runs business logic and exposes APIs for clients. The typical architecture is client–server, where clients initiate requests and servers respond. Communication follows standard protocols such as HTTP/HTTPS, FTP, SMTP, DNS, and various database or RPC protocols. Servers are designed for reliability and can employ redundancy, load balancing, backups, and monitoring to maintain service availability.

Management concerns include security, access control, performance tuning, and patching. Server operating systems include Linux distributions, Windows Server, and UNIX variants, while deployment can involve physical hardware, virtual machines, containers, or cloud services. The term can also refer to the software component that performs the service, not only the machine hosting it. Historically, servers emerged with early centralized networks and have become foundational to modern computing.