Networks

A computer network is a number of computers linked together to allow them to share resources.

Networked computers can share:

• hardware - such as a printer
• software - they may be able to load up the same program
• data - they can load up the same files

LANs and WANs

There are two types of network: LAN and WAN.

A LAN is a Local Area Network covering a small area such as one building e.g. in a school or a college.

A WAN is a Wide Area Network covering a large geographical area.

• The Internet is a WAN.
• A network of bank cash dispensers is a WAN.
• A school network is a LAN. LANs are often connected to WANs, for example a school network could be connected to the Internet.
  

Telephone lines are often used to connect WANs. LANs use dedicated cables or wireless technology.

Advantages and disadvantages of networks

Advantages

• Sharing devices such as printers saves money.
• Site licences are likely to be cheaper than buying several stand-alone licences.
• Files can easily be shared between users.
• Network users can communicate by email.
• Security is good - users cannot see other users' files unlike on stand-alone machines.
• A file server is easy to back up as all the data is stored in one place.

Disadvantages

• Purchasing the network cabling and file servers can be expensive.
• Managing a large network is complicated, requires training and a network manager usually needs to be employed.
• If the file server breaks down the files on the file server become inaccessible. E-mail might still work if it is on a separate server. The computers can still be used as stand alones.
• Viruses can spread to other computers throughout a computer network.
• There is a danger of hacking, particularly with wide area networks. Security procedures are needed to prevent such abuse.