Editing Server (computing) (section)

== Purpose ==
{{main category|Servers (computing)}}
The role of a server is to share data as well as to share [[System resource|resources]] and distribute work. A server computer can serve its own computer programs as well; depending on the scenario, this could be part of a ''[[quid pro quo]]'' transaction, or simply a technical possibility. The following table shows several scenarios in which a server is used.
{| class="wikitable"
|-
!Server type
!Purpose
!Clients
|-
|[[Application server]]
|Hosts application [[Frontend and backend|back ends]] that user clients (front ends, [[web app]]s or locally installed applications) in the network connect to and use. These servers do not need to be part of the [[World Wide Web]]; any [[local network]] would do.
|Clients with a browser or a local front end, or a web server
|-
|[[Catalog server]]
|Maintains an index or table of contents of information that can be found across a large distributed network, such as computers, users, files shared on file servers, and web apps. [[Directory server]]s and [[name server]]s are examples of catalog servers.
|Any computer program that needs to find something on the network, such a [[Windows domain|Domain member]] attempting to log in, an [[email client]] looking for an email address, or a user looking for a file
|-
|[[Communications server]]
|Maintains an environment needed for one communication endpoint (user or devices) to find other endpoints and communicate with them. It may or may not include a directory of communication endpoints and a presence detection service, depending on the openness and security parameters of the network
|Communication endpoints (users or devices)
|-
|[[Supercomputer|Computing server]]
|Shares vast amounts of computing resources, especially [[Central processing unit|CPU]] and [[random-access memory]], over a network.
|Any computer program that needs more CPU power and RAM than a personal computer can probably afford. The client must be a networked computer; otherwise, there would be no client-server model.
|-
|[[Database server]]
|Maintains and shares any form of [[database]] (organized collections of data with predefined properties that may be displayed in a table) over a network.
|[[Spreadsheet]]s, [[accounting software]], [[Digital asset management|asset management software]] or virtually any computer program that consumes well-organized data, especially in large volumes
|-
|[[Fax server]]
|Shares one or more [[fax machine]]s over a network, thus eliminating the hassle of physical access
|Any fax sender or recipient
|-
|[[File server]]
|Shares [[Computer file|files]] and [[Computer folder|folders]], storage space to hold files and folders, or both, over a network
|Networked computers are the intended clients, even though local programs can be clients
|-
|[[Game server]]
|Enables several computers or gaming devices to play [[multiplayer video game]]s
|Personal computers or [[Video game console|gaming consoles]]
|-
|[[Mail server]]
|Makes [[email]] communication possible in the same way that a [[post office]] makes [[snail mail]] communication possible
|Senders and recipients of email
|-
|[[Media server]]
|Shares [[digital video]] or [[digital audio]] over a network through [[Streaming media|media streaming]] (transmitting content in a way that portions received can be watched or listened to as they arrive, as opposed to downloading an entire file and then using it)
|User-attended personal computers equipped with a monitor and a speaker
|-
|[[Print server]]
|Shares one or more [[Printer (computing)|printers]] over a network, thus eliminating the hassle of physical access
|Computers in need of printing something
|-
|[[Sound server]]
|Enables computer programs to play and record sound, individually or cooperatively
|Computer programs of the same computer and network clients.
|-
|[[Proxy server]]
|Acts as an [[intermediary]] between a client and a server, accepting incoming traffic from the client and sending it to the server. Reasons for doing so include content control and filtering, improving traffic performance, preventing unauthorized network access or simply routing the traffic over a large and complex network.
|Any networked computer
|-
|[[Virtual private server|Virtual server]]
|Shares hardware and software resources with other virtual servers. It exists only as defined within specialized software called [[hypervisor]]. The [[hypervisor]] presents virtual hardware to the server as if it were real physical hardware.<ref>{{cite web |last1=IT Explained |title=Server - Definition and Details |url=https://www.paessler.com/it-explained/server |website=www.paessler.com |language=en}}</ref> Server virtualization allows for a more efficient infrastructure.<ref>{{cite web |last1=IT Explained |title=DNS Server Not Responding |url=https://dnsservernotresponding.org/ |website=www.dnsservernotresponding.org |language=en |access-date=2020-02-11 |archive-date=2020-09-26 |archive-url=https://web.archive.org/web/20200926091559/https://dnsservernotresponding.org/ |url-status=dead }}</ref>
|Any networked computer
|-
|[[Web server]]
|Hosts [[web page]]s. A web server is what makes the [[World Wide Web]] possible. Each [[website]] has one or more web servers. Also, each server can host multiple websites.
|Computers with a web browser
|}
Almost the entire structure of the [[Internet]] is based upon a [[client–server]] model. High-level [[root nameserver]]s, [[Domain Name System|DNS]], and routers direct the traffic on the internet. There are millions of servers connected to the Internet, running continuously throughout the world<ref>{{cite web|title=Web Servers|url=http://www.serverwatch.com/stypes/index.php/V2Vi|publisher=IT Business Edge|access-date=July 31, 2013}}</ref> and virtually every action taken by an ordinary [[Internet]] user requires one or more interactions with one or more servers. There are exceptions that do not use dedicated servers; for example, [[File sharing|peer-to-peer file sharing]] and some implementations of [[telephony]] (e.g. pre-Microsoft [[Skype]]).