Computer networks - a system of interconnected computers and computerized peripherals such as printers. This interconnection among computers facilitates information sharing among them. Computers may connect to each other by either wired or wireless media. Networks on the basis of their scale, scope and purpose, can be categorized as:

1. Local area network (LAN).
2. Wide area network (WAN)
3. Metropolitan area network (MAN)
4. Personal area network (PAN)
5. Virtual private network (VPN)
6. Campus area network (CAN)
7. Enterprise private network
8. Home area network
9. Storage area networks

I’d like to explain all of them:

1. Local area network: consists of a computer network at a single site, typically an individual office building. A LAN is very useful for sharing resources, such as data storage and printers. LANs can be built with relatively inexpensive hardware, such as hubs, network adapters and Ethernet cables. The smallest LAN may only use two computers, while larger LANs can accommodate thousands of computers. A LAN typically relies mostly on wired connections for increased speed and security, but wireless connections can also be part of a LAN. High speed and relatively low cost are the defining characteristics of LANs. LANs are typically used for single sites where people need to share resources among themselves but not with the rest of the outside world. Think of an office building where everybody should be able to access files on a central server or be able to print a document to one or more central printers. Those tasks should be easy for everybody working in the same office, but you would not want somebody just walking outside to be able to send a document to the printer from their cell phone! If a local area network, or LAN, is entirely wireless, it is referred to as a wireless local area network, or WLAN.

2. Wide area network: As the name suggests, the Wide Area Network (WAN) covers a wide area which may span across provinces and even a whole country. Generally, telecommunication networks are Wide Area Network. These networks provide connectivity to MANs and LANs. Since they are equipped with very high speed backbone, WANs use very expensive network equipment.

3. Metropolitan area network: MANs connect multiple geographically nearby LANs to one another (over an area of up to a few dozen kilometers) at high speeds. Thus, a MAN lets two remote nodes communicate as if they were part of the same local area network. A MAN is made from switches or routers connected to one another with high-speed links (usually fiber optic cables).

4. Personal area network: A PAN is a computer network used for communication among computer and other communicating and information giving devices. Some examples used of devices used in a Pan are personal computers, printers, fax machines and telephones. A PAN may include wired and wireless connections between devices.

5. Virtual private network: A virtual private network (VPN) allows the provisioning of private network services for an organization or organizations over a public or shared infrastructure such as the Internet or service provider backbone network. The shared service provider backbone network is known as the VPN backbone and is used to transport traffic for multiple VPNs, as well as possibly non-VPN traffic.

6. Campus area network: A campus network is a computer network covering an area of several LANs but smaller than a MAN. A CAN may cover a college, university and areas like hostels.

7. Enterprise private network: An enterprise private network is a computer network built by a business to interconnect its various company sites (such as production sites, offices and shops) in order to share computer resources. Network diagrams visualize schematically the computer networks topology, equipment nodes and different types of their logical and physical connections. They are used by IT professionals to visually document the topology and design of computer and telecommunication networks.

8. Home area network: A home area network is a network that is deployed and operated within a small boundary, typically a house or small office/home office (SOHO). It enables the communication and sharing of resources (like the Internet) between computers, mobile and other devices over a network connection.

9. Storage area network: This network connects servers directly to devices which store amounts of data without relying on a LAN or WAN network to do so. This can involve another type of connection known as Fiber Channel, a system similar to Ethernet which handles high-performance disk storage for applications on a number of professional networks.

Computer networks have many uses, both for companies and for individuals, in the home and while on the move. Companies use networks of computers to share corporate information, typically using the client-server model with employee desktops acting as clients accessing powerful servers in the machine room. For individuals, networks offer access to a variety of information and entertainment resources, as well as a way to buy and sell products and services. Individuals often access the Internet via their phone or cable providers at home, though increasingly wireless access is used for laptops and phones. Technology advances are enabling new kinds of mobile applications and networks with computers embedded in appliances and other consumer devices. The same advances raise social issues such as privacy concerns.