A server is a program that functions as a socket listener. The term server can also be used to generally describe a host that is positioned to carry out one or more such programs. A server functions as either sole-operating software, or one or series of computers that links other electronic devices together. In addition, they often provide important and necessary services to members, both public and private, across an entire network through the Internet. For example, when a query is entered in a search engine, the query is sent via the Internet from the computer to the server that stores all the web pages that are relevant to the query. Then, the server sends the results back to the computer.

The term server is widely used in the world of information technology. Although there are many server-specific products available, any computerized route that shares a resource to one or more client processes is considered a server. For example, in file sharing, the existence of files on a machine does not classify it as a server. However, the mechanism that shares these files to clients by the operating system is the server. In terms of hardware, the term server usually specifies computer models that are intended for hosting software applications in a network. Nearly any personal computer is capable of acting as a network server; however, a true dedicated server will contain features that make it more suitable for production environments. These features can include a faster CPU, increased high-performance RAM, or more than one hard drive.
Hardware requirements for servers vary with different server applications. Due to the fact that a server’s duties are to provide service to multiple users over a network, different requirements such as quick network connections and high I/O throughput are important. Servers may run in headless node without an input device since they are accessed via a network. They often run for long periods of time without interruption and with high availability, making hardware reliability and durability very important. Although servers can be built from product computer parts, mission-critical servers use specialized hardware with few failure rates in order to maximize speed. Hardware redundancy, which is when more than one instance of modules such as power supplies and hard disks are installed and arranged so that if one fails another is automatically available, is commonly used.

Though not deemed as actual servers, some operating systems such as Microsoft Windows seem to be designed with a client”“server structure in mind. In a sense, the operating system can be seen as serving hardware to the software. They can also run programs in the background called services, which may wait in a sleep state until they are needed. Since virtually any software that provides services can be called a server, modern personal computers can be seen as an abundant array of servers and clients operating in parallel. Server-oriented operating systems tend to have certain features in common that make them more suitable for the server environment, such as the ability to reconfigure and update hardware and software without having to restart, advanced backup services to allow regular and frequent online backups of critical data, transparent data transfer between different devices, and tight system security. In many cases, these server-oriented operating systems can interact with hardware sensors to identify conditions such as overheating or disk failure, and take accurate measures to fix the problem.

The Internet itself is also a bunch of servers and clients. Just about every action taken by an ordinary Internet user requires one or more interactions with one or more servers, and almost the whole structure of the Internet is based upon a client”“server model. High-level root nameservers, DNS servers, and routers direct the traffic on the internet, and there are millions of servers connected to the Internet, running continuously throughout the world. Some examples of these are the World Wide Web, e-mail, chat and instant messaging, streaming audio and video, online gaming, and database servers.