A server operating system is software that was especially developed to serve as a platform for running multi-user computer programs, applications that are networked and programs critical to business computing. This type of operating system (OS) often comes bundled with the most common types of applications deployed in the client-server model, a term used to indicate the exchange of information between computers. For example, a hypertext transfer protocol (HTTP) or web server hosts or "holds" the text files, images files and scripts that work together to form a website. When someone connects to the Internet and types in a web address, the server that holds the files of the site delivers or "serves" the requested pages to the client computer or the machine that made the request.
Frequently used applications in the client-server model handle operations for sharing files and printers across a network, hosting and serving web pages via the Internet, terminal services and the sending and receiving of email. This type of computing might be required when there's the need or desire to host one's own website locally when a domain is owned, to establish an intranet to disseminate information and allow communication strictly among employees of a company, to allow multiple computers to share a common printer or to set up a network drive on which files are stored and accessible by a select group of people. The server operating system is the platform under which applications to carry out each of these operations are run.
There are many factors that should be taken into consideration in the selection of a server operating system. They include determining the amount of money one can afford to spend, the hardware requirements of the system, the applications that are included or "bundled" into the software, the power of the hardware and the system, security, scalability, administrative tools available and options to install third-party programs. Consideration of administrative tools and knowledge of how to use them also is important because a server operating system does not tend to be nearly as user-friendly as systems for non-commercial, single-user purposes are.
If the number of requests that client computers will be making of the server is very high, a very powerful server that can run on hardware with a very large storage capacity and multiple processors usually is needed to prevent downtime. Other hardware considerations are dictated by the specific server operating system of choice. Stability also is of extreme importance; if a web server hosting a commercial website breaks down, a company's sales could plummet and affect profits. Consideration of the availability of crucial applications that can run under the server operating system also is very important because if what is needed is not included, there will be the need to install third-party programs to satisfy computing needs such as the handling of company emails.
Security also is of great importance when choosing and working with a server operating system. One way to help reduce the risk of attacks is to set up what are known as dedicated servers, which are platforms dedicated to handling only one type of request from client computers. For example, an email server would process only requests related to the sending and receiving of company email; it would not be involved in handling the multiple requests that can be generated by computers sharing a common printer. Sometimes, information technology (IT) specialists will even set up one server to handle incoming mail and another to handle outgoing mail.