- Great Painters
- Accounting
- Fundamentals of Law
- Marketing
- Shorthand
- Concept Cars
- Videogames
- The World of Sports

- Blogs
- Free Software
- Google
- My Computer

- PHP Language and Applications
- Wikipedia
- Windows Vista

- Education
- Masterpieces of English Literature
- American English

- English Dictionaries
- The English Language

- Medical Emergencies
- The Theory of Memory
- The Beatles
- Dances
- Microphones
- Musical Notation
- Music Instruments
- Batteries
- Nanotechnology
- Cosmetics
- Diets
- Vegetarianism and Veganism
- Christmas Traditions
- Animals

- Fruits And Vegetables


  1. Adobe Reader
  2. Adware
  3. Altavista
  4. AOL
  5. Apple Macintosh
  6. Application software
  7. Arrow key
  8. Artificial Intelligence
  9. ASCII
  10. Assembly language
  11. Automatic translation
  12. Avatar
  13. Babylon
  14. Bandwidth
  15. Bit
  16. BitTorrent
  17. Black hat
  18. Blog
  19. Bluetooth
  20. Bulletin board system
  21. Byte
  22. Cache memory
  23. Celeron
  24. Central processing unit
  25. Chat room
  26. Client
  27. Command line interface
  28. Compiler
  29. Computer
  30. Computer bus
  31. Computer card
  32. Computer display
  33. Computer file
  34. Computer games
  35. Computer graphics
  36. Computer hardware
  37. Computer keyboard
  38. Computer networking
  39. Computer printer
  40. Computer program
  41. Computer programmer
  42. Computer science
  43. Computer security
  44. Computer software
  45. Computer storage
  46. Computer system
  47. Computer terminal
  48. Computer virus
  49. Computing
  50. Conference call
  51. Context menu
  52. Creative commons
  53. Creative Commons License
  54. Creative Technology
  55. Cursor
  56. Data
  57. Database
  58. Data storage device
  59. Debuggers
  60. Demo
  61. Desktop computer
  62. Digital divide
  63. Discussion groups
  64. DNS server
  65. Domain name
  66. DOS
  67. Download
  68. Download manager
  69. DVD-ROM
  70. DVD-RW
  71. E-mail
  72. E-mail spam
  73. File Transfer Protocol
  74. Firewall
  75. Firmware
  76. Flash memory
  77. Floppy disk drive
  78. GNU
  79. GNU General Public License
  80. GNU Project
  81. Google
  82. Google AdWords
  83. Google bomb
  84. Graphics
  85. Graphics card
  86. Hacker
  87. Hacker culture
  88. Hard disk
  89. High-level programming language
  90. Home computer
  91. HTML
  92. Hyperlink
  93. IBM
  94. Image processing
  95. Image scanner
  96. Instant messaging
  97. Instruction
  98. Intel
  99. Intel Core 2
  100. Interface
  101. Internet
  102. Internet bot
  103. Internet Explorer
  104. Internet protocols
  105. Internet service provider
  106. Interoperability
  107. IP addresses
  108. IPod
  109. Joystick
  110. JPEG
  111. Keyword
  112. Laptop computer
  113. Linux
  114. Linux kernel
  115. Liquid crystal display
  116. List of file formats
  117. List of Google products
  118. Local area network
  119. Logitech
  120. Machine language
  121. Mac OS X
  122. Macromedia Flash
  123. Mainframe computer
  124. Malware
  125. Media center
  126. Media player
  127. Megabyte
  128. Microsoft
  129. Microsoft Windows
  130. Microsoft Word
  131. Mirror site
  132. Modem
  133. Motherboard
  134. Mouse
  135. Mouse pad
  136. Mozilla Firefox
  137. Mp3
  138. MPEG
  139. MPEG-4
  140. Multimedia
  141. Musical Instrument Digital Interface
  142. Netscape
  143. Network card
  144. News ticker
  145. Office suite
  146. Online auction
  147. Online chat
  148. Open Directory Project
  149. Open source
  150. Open source software
  151. Opera
  152. Operating system
  153. Optical character recognition
  154. Optical disc
  155. output
  156. PageRank
  157. Password
  158. Pay-per-click
  159. PC speaker
  160. Peer-to-peer
  161. Pentium
  162. Peripheral
  163. Personal computer
  164. Personal digital assistant
  165. Phishing
  166. Pirated software
  167. Podcasting
  168. Pointing device
  169. POP3
  170. Programming language
  171. QuickTime
  172. Random access memory
  173. Routers
  174. Safari
  175. Scalability
  176. Scrollbar
  177. Scrolling
  178. Scroll wheel
  179. Search engine
  180. Security cracking
  181. Server
  182. Simple Mail Transfer Protocol
  183. Skype
  184. Social software
  185. Software bug
  186. Software cracker
  187. Software library
  188. Software utility
  189. Solaris Operating Environment
  190. Sound Blaster
  191. Soundcard
  192. Spam
  193. Spamdexing
  194. Spam in blogs
  195. Speech recognition
  196. Spoofing attack
  197. Spreadsheet
  198. Spyware
  199. Streaming media
  200. Supercomputer
  201. Tablet computer
  202. Telecommunications
  203. Text messaging
  204. Trackball
  205. Trojan horse
  206. TV card
  207. Unicode
  208. Uniform Resource Identifier
  209. Unix
  210. URL redirection
  211. USB flash drive
  212. USB port
  213. User interface
  214. Vlog
  215. Voice over IP
  216. Warez
  217. Wearable computer
  218. Web application
  219. Web banner
  220. Web browser
  221. Web crawler
  222. Web directories
  223. Web indexing
  224. Webmail
  225. Web page
  226. Website
  227. Wiki
  228. Wikipedia
  229. WIMP
  230. Windows CE
  231. Windows key
  232. Windows Media Player
  233. Windows Vista
  234. Word processor
  235. World Wide Web
  236. Worm
  237. XML
  238. X Window System
  239. Yahoo
  240. Zombie computer

This article is from:

All text is available under the terms of the GNU Free Documentation License: 

Server (computing)

From Wikipedia, the free encyclopedia


In information technology, a server is a computer system that provides services to other computing systems—called clients—over a network. The term server can refer to hardware (such as a Sun computer system) or software (such as an RDBMS server).


A server rack
A server rack
Above server rack seen from the back
Above server rack seen from the back

Servers occupy a place in computing similar to that occupied by minicomputers in the past, which they have largely replaced. The typical server is a computer system that operates continuously on a network and waits for requests for services from other computers on the network. Many servers are dedicated to this role, but some may also be used simultaneously for other purposes, particularly when the demands placed upon them as servers are modest. For example, in a small office, a large desktop computer may act as both a desktop workstation for one person in the office and as a server for all the other computers in the office. The term 'Server' originates from the word 'Serve', therefore this computer system is mainly serving the whole network that it is connected to in any form, whether by queueing up the printing jobs of several users, to even acting as a file server for applications that online terminals could access. The name 'Server' is another term given to 'Host computers'.

Servers today are physically similar to most other general-purpose computers, although their hardware configurations may be particularly optimized to fit their server roles, if they are dedicated to that role. Many use hardware identical or nearly identical to that found in standard desktop PCs. However, servers run software that is often very different from that used on desktop computers and workstations.

Servers should not be confused with mainframes, which are very large computers that centralize certain information-processing activities in large organizations and may or may not act as servers in addition to their other activities. Many large organizations have both mainframes and servers, although servers usually are smaller and much more numerous and decentralized than mainframes.

Servers frequently host hardware resources that they make available on a controlled and shared basis to client computers, such as printers (print servers) and file systems (file servers). This sharing permits better access control (and thus better security) and can reduce costs by reducing duplication of hardware.


Servers have come into being in parallel with computer networks. Networks allow computers to communicate with each other, and an outgrowth of this was the tendency to dedicate some computers to a serving role while other computers (those that interact directly with human users) assume a client role. Server computers and their associated software evolved to fill the server role.

As networks have grown and developed, so have servers; and minicomputers—small computers larger than a desktop computer but more modest than a mainframe—have been largely driven out of existence in consequence, their niche partially disappearing and partially being absorbed into that of servers.

The rise of corporate computer networks and the Internet among ordinary home and office users have provided a very powerful impetus to the development of server.

Server hardware

Although servers can be built from commodity computer components—particularly for low-load and/or non-critical applications—dedicated, high-load, mission-critical servers use specialized hardware that is optimized for the needs of servers.

For example, servers may incorporate “industrial-strength” mechanical components such as disk drives and fans that provide very high reliability and performance at a correspondingly high price. Aesthetic considerations are ignored, since most servers operate in unattended computer rooms and are only visited for maintenance or repair purposes. Although servers usually require large amounts of disk space, smaller disk drives may still be used in a trade-off of capacity vs. reliability. CPU speeds are far less critical for many servers than they are for many desktops. Not only are typical server tasks likely to be delayed more by I/O requests than processor requirements, but the lack of any graphic user interface in many servers frees up very large amounts of processing power for other tasks, making the overall processor power requirement lower. If a great deal of processing power is required in a server, there is a tendency to add more CPUs rather than increase the speed of a single CPU, again for reasons of reliability and redundancy.

The lack of a GUI in a server (or the rare need to use it) makes it unnecessary to install expensive video adapters. Similarly, elaborate audio interfaces, joystick connections, USB peripherals, and the like are usually unnecessary.

Because servers must operate continuously and reliably, noisy but efficient and trustworthy fans may be used for ventilation instead of inexpensive and quiet fans; and in some cases, centralized air-conditioning may be used to keep servers cool, instead of or in addition to fans. Special uninterruptible power supply may be used to ensure that the servers continue to run in the event of a power failure.

All servers include heavy-duty network connections in order to allow them to handle the large amounts of traffic that they typically receive and generate as they receive and reply to client requests.

Server software

The major difference between servers and desktop computers is not in the hardware but in the software. Servers often run operating systems that are designed specifically for use in servers. They also run special applications that are designed specifically to carry out server tasks.

Operating systems

The Microsoft Windows operating system is predominant among desktop computers, but in the world of servers, the most popular operating systems—such as FreeBSD, Solaris, and GNU/Linux—are derived from or similar to the UNIX operating system. UNIX was originally a minicomputer operating system, and as servers gradually replaced traditional minicomputers, UNIX was a logical and efficient choice of operating system for the servers.

Server-oriented operating systems tend to have certain features in common that make them more suitable for the server environment, such as the absence of a GUI (or an optional GUI); the ability to be reconfigured (in both hardware and software) to at least some extent without stopping the system; advanced backup facilities to permit online backups of critical data at regular and frequent intervals; facilities to enable the movement of data between different volumes or devices in such a way that is transparent to the end user; flexible and advanced networking capabilities; features (such as daemons in UNIX or services in Windows) that make unattended execution of programs more reliable; tight system security, with advanced user, resource, data, and memory protection, and so on. Server-oriented operating systems in many cases can interact with hardware sensors to detect conditions such as overheating, processor and disk failure, and either alert an operator, take remedial action, or both, depending on the configuration.

Because the requirements of servers are, in some cases, almost diametrically opposed to those of desktop computers, it is extremely difficult to design an operating system that handles both environments well; thus, operating systems that are well suited to the desktop may not be ideal for servers and vice versa. Nevertheless, certain versions of Windows are also used on a minority of servers as are recent versions of the popular Mac OS X (which is Unix-based, and gives users complete access to the Unix operating system) family of desktop operating systems and even some proprietary mainframe operating systems (such as z/OS); but the dominant operating systems among servers continues to be UNIX versions or clones. Even in the case of GNU/Linux, a popular UNIX-like operating system frequently used on servers, configurations that are ideal for servers may be unsatisfactory for desktop use, and configurations that perform well on the desktop may leave much to be desired on servers.

The rise of the microprocessor-based server was facilitated by the development of several versions of the Unix operating system to run on the Intel x86 microprocessor architecture, including Solaris, GNU/Linux and FreeBSD. The Microsoft Windows family of operating systems also runs on Intel hardware, and versions beginning with Windows NT have incorporated features making them suitable for use on servers.

Whilst the role of server and desktop operating systems remains distinct, improvements in both hardware performance and reliability and operating system reliability have blurred the distinction between these two classes of system, which at one point remained largely separate in terms of code base, hardware and vendor providers. Today, many desktop and server operating systems share the same code base, and differ chiefly in terms of configuration. Furthermore, the rationalisation of many corporate applications towards web-based and middleware platforms has lessened the demand for specialist application servers.

Server applications

Server applications are tailored to the tasks performed by servers just as desktop or mainframe applications are tailored to their own respective environments.

Most server applications are distinguished by the fact that they are completely non-interactive on the local server itself; that is, they do not display information on a screen and do not expect user input. Instead, they run unobtrusively within the server and interact only with client computers on the network to which the server is attached. Applications of this kind are called daemons in UNIX terminology, and services in Windows terminology.

Server applications are typically started once when the server is booted, and thereafter run continuously until the server is stopped. A given server usually runs the same set of applications at all times, since there is no way for the server to predict when a given service might be requested of it by a client computer. Some server applications in some server systems are automatically started when a request from a client is received, and are then stopped when request has been satisfied.

Servers on the Internet

Almost the entire structure of the Internet is based upon a client-server model. Many millions of servers are connected to the Internet and run continuously throughout the world.

Among the many services provided by Internet servers are: the Web; the Domain Name System; electronic mail; file transfer; instant messaging; streaming audio and video, online gaming, and countless others. Virtually every action taken by an ordinary Internet user requires one or more interactions with one or more servers.

See also

  • Blade server

External links

  • SUN Servers
  • IBM Servers
  • HP Servers
  • Dell Servers
  • Motorola Communications Servers
Retrieved from ""