Networking is nothing but you can connect one or more computers in a group and try to exchange their data's and resources from one computer to another computer. There are different Networks are there.
LAN = Local Area Network
WAN=Wide Area Nertwork
Read this full...You get more informations very clearly..!
A computer network is multiple computers connected together using a telecommunication system for the purpose of communicating and sharing resources.
Experts in the field of networking debate whether two computers that are connected together using some form of communications medium constitute a network. Therefore, some works state that a network requires three connected computers. For example, "Telecommunications: Glossary of Telecommunication Terms" [1] states that a computer network is "A network of data processing nodes that are interconnected for the purpose of data communication", the term "network" being defined in the same document as "An interconnection of three or more communicating entities". A computer connected to a non-computing device (e.g., networked to a printer via an Ethernet link) may also represent a computer network, although this article does not address this configuration.
This article uses the definition which requires two or more computers to be connected together to form a network.[2] The same basic functions are generally present in this case as with larger numbers of connected computers.
Basic components of computer networks
Computers
Many of the components of an average network are individual computers, which are generally either workstations (including personal computers) or servers.
Types of workstations
There are many types of workstations that may be incorporated into a particular network, some of which have high-end displays, multiple CPUs, large amounts of RAM, large amounts of hard drive storage space, or other enhancements required for special data processing tasks, graphics, or other resource intensive applications. (See also network computer).
Types of servers
The following lists some common types of servers and their purpose.
File server
Stores various types of files and distributes them to other clients on the network.
Print server
Controls and manages one or more printers and accepts print jobs from other network clients, spooling the print jobs, and performing most or all of the other functions that a workstation would perform to accomplish a printing task if the printer were connected directly to the workstation's printer port.
Mail server
Stores, sends, receives, routes, and performs other email related operations for other clients on the network.
Fax server
Stores, sends, receives, routes, and performs other functions necessary for the proper transmission, reception, and distribution of faxes.
Telephony server
Performs telephony related functions such as answering calls automatically, performing the functions of an interactive voice response system, storing and serving voice mail, routing calls between the Public Switched Telephone Network (PSTN) and the network or the Internet (e.g., voice over IP (VoIP) gateway), etc.
Proxy server
Performs some type of function on behalf of other clients on the network to increase the performance of certain operations (e.g., prefetching and caching documents or other data that are requested very frequently) or as a security precaution to isolate network clients from external threats.
Remote Access Server (RAS)
Monitors modem lines or other network communications channels for requests to connect to the network from a remote location, answers the incoming telephone call or acknowledges the network request, and performs the necessary security checks and other procedures necessary to log a user onto the network.
Application server
Performs the data processing or business logic portion of a client application, accepting instructions for operations to perform from a workstation and serving the results back to the workstation, while the workstation performs the user interface or GUI portion of the processing (i.e., the presentation logic) that is required for the application to work properly.
Web server
Stores HTML documents, images, text files, scripts, and other Web related data (collectively known as content), and distributes this content to other clients on the network on request.
Backup server
Has network backup software installed and has large amounts of hard drive storage or other forms of storage (tape, etc.) available to it to be used for the purpose of ensuring that data loss does not occur in the network.'''
Game server
Dedicated computer system running game hosting software. Most run 24/7.
Printers
Many printers are capable of acting as part of a computer network without any other device, such as a print server, to act as an intermediary between the printer and the device that is requesting a print job to be completed.
Thin Clients
Many networks use thin clients instead of workstations either for data entry and display purposes or in some cases where the application runs entirely on the server.
Other devices
There are many other types of devices that may be used to build a network, many of which require an understanding of more advanced computer networking concepts before they are able to be easily understood (e.g., hubs, routers, bridges, switches, hardware firewalls, etc.). On home and mobile networks, connecting consumer electronics devices such as video game consoles is becoming increasingly common.
Building a computer network
A simple network
A simple computer network may be constructed from two computers by adding a network adapter (Network Interface Controller (NIC)) to each computer and then connecting them together with a special cable called a crossover cable. This type of network is useful for transferring information between two computers that are not normally connected to each other by a permanent network connection or for basic home networking applications. Alternatively, a network between two computers can be established without dedicated extra hardware by using a standard connection such as the RS-232 serial port on both computers, connecting them to each other via a special crosslinked null modem cable.
Practical networks
Practical networks generally consist of more than two interconnected computers and generally require special devices in addition to the Network Interface Controller that each computer needs to be equipped with. Examples of some of these special devices are listed above under Basic Computer Network Building Blocks / Other devices.
Types of networks:
Below is a list of the most common types of computer networks.
A personal area network (PAN) :
A personal area network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person. The devices may or may not belong to the person in question. The reach of a PAN is typically a few meters. PANs can be used for communication among the personal devices themselves (intrapersonal communication), or for connecting to a higher level network and the Internet (an uplink).
Personal area networks may be wired with computer buses such as USB and FireWire. A wireless personal area network (WPAN) can also be made possible with network technologies such as IrDA and Bluetooth.
Local Area Network (LAN):
A network that is limited to a relatively small spatial area such as a room, a single building, a ship, or an aircraft. Local area networks are sometimes called a single location network.
Note: For administrative purposes, large LANs are generally divided into smaller logical segments called workgroups. A workgroup is a group of computers that share a common set of resources within a LAN.
Campus Area Network (CAN):
A network that connects two or more LANs but that is limited to a specific (possibly private) geographical area such as a college campus, industrial complex, or a military base
Note: A CAN is generally limited to an area that is smaller than a Metropolitan Area Network.
Metropolitan Area Network (MAN):
A network that connects two or more Local Area Networks or CANs together but does not extend beyond the boundaries of the immediate town, city, or metropolitan area. Multiple routers, switches & hubs are connected to create a MAN
Wide Area Networks (WAN):
A WAN is a data communications network that covers a relatively broad geographic area and that often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.
Types of WANs:
Centralized:
A centralized WAN consists of a central computer that is connected to dumb terminals and / or other types of terminal devices.
Distributed:
A distributed WAN consists of two or more computers in different locations and may also include connections to dumb terminals and other types of terminal devices.
Internetwork:
Two or more networks or network segments connected using devices that operate at layer 3 (the 'network' layer) of the OSI Basic Reference Model, such as a router.
Note: Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork.
Internet, The:
A specific internetwork, consisting of a worldwide interconnection of governmental, academic, public, and private networks based upon the Advanced Research Projects Agency Network (ARPANET) developed by ARPA of the U.S. Department of Defense – also home to the World Wide Web (WWW) and referred to as the 'Internet' with a capital 'I' to distinguish it from other generic internetworks.
Intranet:
A network or internetwork that is limited in scope to a single organization or entity or, also, a network or internetwork that is limited in scope to a single organization or entity and which uses the TCP/IP protocol suite, HTTP, FTP, and other network protocols and software commonly used on the Internet.
Note: Intranets may also be categorized as a LAN, CAN, MAN, WAN, or other type of network.
Extranet:
A network or internetwork that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities (e.g., a company's customers may be provided access to some part of its intranet thusly creating an extranet while at the same time the customers may not be considered 'trusted' from a security standpoint).
Note: Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN, because an extranet must have at least one connection with an outside network.
Intranets and extranets may or may not have connections to the Internet. If connected to the Internet, the intranet or extranet is normally protected from being accessed from the Internet without proper authorization. The Internet itself is not considered to be a part of the intranet or extranet, although the Internet may serve as a portal for access to portions of an extranet.
Classification of computer networks
This article or section does not adequately cite its references or sources.
Please help improve this article by adding citations to reliable sources. (help, get involved!)
Any material not supported by sources may be challenged and removed at any time. This article has been tagged since December 2006.
By network layer
Computer networks may be classified according to the network layer at which they operate according to some basic reference models that are considered to be standards in the industry such as the seven layer OSI reference model and the five layer TCP/IP mode.
By scale
Computer networks may be classified according to the scale or extent of reach of the network, for example as a Personal area network (PAN), Local area network (LAN), Campus area network (CAN), Metropolitan area network (MAN), or Wide area network (WAN).
By connection method
Computer networks may be classified according to the technology that is used to connect the individual devices in the network such as HomePNA, Power line communication, Ethernet, or Wireless LAN.
By functional relationship
Computer networks may be classified according to the functional relationships which exist between the elements of the network, for example Active Networking, Client-server and Peer-to-peer (workgroup) architectures. Also, computer networks are used to send data from one to another by the hardrive
By network topology
Computer networks may be classified according to the network topology upon which the network is based, such as Bus network, Star network, Ring network, Mesh network, Star-bus network, Tree or Hierarchical topology network, etc.
Topology can be arranged in a Geometric Arragement
By services provided
Computer networks may be classified according to the services which they provide, such as Storage area networks, Server farms, Process control networks, Value-added network, Wireless community network, etc.